Electronic Signature on Mac: Sign a PDF in Preview

On a Mac, you can add an electronic signature to a PDF using Preview, the built-in app, without printing the document. You can draw a signature with your trackpad, capture one with your camera, or use an iPhone or iPad; first make sure you have the PDF and a way to create your signature.

What You’ll Need

A Mac with the PDF saved locally or accessible in Finder.
Preview, which is included with macOS.
A trackpad, camera, or nearby iPhone or iPad to create your signature. You can also use a mouse to draw one, though it may be less natural.
Permission to sign the document. If it requires a certificate-based digital signature or a specific signing service, Preview’s drawn signature may not meet that requirement.

Step-by-Step

Open the PDF in Preview. In Finder, locate the file and double-click it. If it opens in another app, Control-click the file, choose Open With, then select Preview. You can also open Preview, choose File > Open, and select the PDF.
Show the Markup toolbar. Click the Markup button (a pen tip inside a circle) in the toolbar. If it is not visible, choose View > Show Markup Toolbar. The toolbar contains the controls for adding text, shapes, and signatures.
Open the signature controls. Click the Sign button, which looks like a handwritten signature. Choose Create Signature if you have not made one before. If you already created a signature, select it from the menu to place it on the page.
Choose how to create the signature. Preview may offer a trackpad, camera, or nearby iPhone or iPad. Available choices can vary with your Mac, connected devices, and macOS settings. Pick a method and follow the prompts.
For a trackpad, draw your signature. Click the prompt to begin, then use your finger on the trackpad to write. Press any key when you finish, review the preview, and click Done if it looks right. If you make a mistake, clear it and try again before saving.
For a camera, write on white paper. Sign your name clearly with dark ink, then hold the paper in front of the camera so the signature lines up with the on-screen guide. When the preview is legible, click Done. If the image is faint, crooked, or reversed, adjust the paper and lighting and try again.
For an iPhone or iPad, follow the on-screen prompt. Select the device option, choose the available device if asked, and sign on its screen. Confirm the signature to send it back to Preview. If the device does not appear, check that it is nearby, available, and signed in to the same Apple Account as the Mac; wireless continuity features must also be enabled.
Place and size the signature. Click the signature in the menu, then click where it belongs in the PDF. Drag it to reposition. Use the blue handles around it to resize; keep it within the intended signature field and do not cover other text. For precise placement, zoom in with the toolbar controls or the trackpad gesture supported by your Mac.
Save a signed copy. Choose File > Save to save changes. To preserve the original, use File > Duplicate first, or choose File > Export and save the signed version with a different name. Reopen the saved copy and check that the signature appears in the right place before sending it.

Common Mistakes

Confusing an electronic signature with a certificate-based digital signature. Preview places a visual signature image in a PDF. It does not, by itself, apply a cryptographic certificate or verify the signer’s identity. Follow the recipient’s instructions if they require a particular signing platform, certificate, or audit trail.
Signing the wrong file or overwriting the original. Check the filename and save a separate copy when you may need the untouched document. Be especially careful if the PDF came from an email or shared folder.
Putting the mark in the wrong place. Zoom in, check which page is active, and confirm the signature sits inside the correct field. A PDF can contain several pages or multiple signature lines.
Making the signature too large or too small. Resize it using the handles rather than repeatedly clicking to add another copy. Check the result at normal page size as well as zoomed in.
Assuming a saved mark is an official form field. Preview’s signature annotation may not fill a form field or satisfy a document workflow. If the PDF has dedicated signing instructions, use the requested method.

Tips

Create a signature that is clear and readable at the size it will appear in the document. A short, steady trackpad signature is often easier than trying to reproduce every detail.
Use the camera method in even light and hold the paper flat. A clean, dark signature on plain white paper generally gives the camera a clearer image.
Once you create a signature, Preview can offer it again from the Sign menu. Treat a saved signature like a personal mark: use a Mac account you control, and remove signatures you no longer want available through the signature menu’s management option if one is shown.
Inspect the final PDF after saving. Check every page, the signature’s position, and whether any typed fields or content were accidentally covered.
If you need to send the PDF, use the signed copy and follow the recipient’s directions for file type and delivery. Avoid sharing a document through an unintended public link.

Troubleshooting

The Markup or Sign button is missing: Open the file in Preview rather than a browser or another PDF app, then choose View > Show Markup Toolbar. If the toolbar is cramped, widen the Preview window or look for additional toolbar controls.
The PDF will not let you add or save a signature: The file may be locked, read-only, or restricted. Check the file’s permissions in Finder and whether you can save a copy. If it is protected, ask the document owner for an editable copy or the approved signing process; do not try to bypass restrictions.
The signature looks poor: Delete the misplaced mark and create it again. For trackpad signing, use a clean, dry finger and slower strokes. For camera signing, improve the lighting, use plain paper, and align the writing with the guide.
Your iPhone or iPad is not listed: Keep it close to the Mac, confirm both devices are available and signed in to the same Apple Account, and check that Wi-Fi and Bluetooth are on. Restarting Preview or the devices can help. If the option remains unavailable, use the trackpad or camera instead.
The signature moves or disappears after saving: Save the PDF, close it, and reopen the saved file in Preview. If the mark is absent, try File > Export to create a new PDF copy, then inspect that copy. Keep the original until you have verified the exported version.

Frequently Asked Questions

Is Preview’s signature legally valid?
Rules and recipient requirements vary by document and location. Preview adds a visible electronic mark, but it does not establish identity or provide a certificate-based digital signature. Confirm the required signing method with the recipient.

Can I sign a PDF on a Mac without printing it?
Yes. Preview lets you create a signature using a trackpad, camera, or supported nearby Apple device, then place it directly on the PDF.

Can I reuse my signature?
Preview can save signatures and make them available from the Sign menu. Use a private Mac account and remove saved signatures you do not want retained.

Can I add a signature in Pages or Word?
You can add images or use app-specific signing features, but the steps differ. If the finished document must be a signed PDF, export it and check the PDF in Preview afterward.

How do I remove a signature I just added?
Choose Edit > Undo soon after placing it. Otherwise, click the signature annotation and press Delete or Backspace. If it is no longer an editable annotation, return to an earlier copy or export before signing.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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