How to Sign a PDF on Mac: Preview, Trackpad and Browser Methods

Macs come with one of the best free PDF signing tools available: Preview. You can create a signature with your trackpad or by holding a signed piece of paper up to the camera, then reuse it on any document.

Method 1: Preview with the trackpad

1. Open the PDF in Preview (double-click usually does this).
2. Click the Markup button (pen tip icon) to show the toolbar.
3. Click the Sign button (a signature squiggle).
4. Choose Trackpad, click the prompt, and sign with your finger on the trackpad.
5. Press any key when done, then click Done.
6. Choose the signature from the Sign menu; it lands on the page. Drag and resize it into place.
7. Save with Cmd+S.

Tip: sign slowly and larger than you think. Trackpad signatures look best when you use the full trackpad.

Method 2: Preview with the camera

This gives the most natural-looking result.

1. Sign your name in black ink on white paper.
2. In Preview, open Sign and choose Camera.
3. Hold the paper up to the camera so the signature sits on the blue line.
4. Preview captures it automatically when it looks right. Click Done.

The signature is stored in your Mac (and syncs across devices if you use iCloud), ready for future documents.

Method 3: a browser editor

If Preview struggles with the file, or you want typed signatures and stamps:

1. Open Docento.app in Safari, Chrome or Firefox.
2. Choose your PDF.
3. Select the signature tool and draw, type, or upload an image of your signature.
4. Place it, add the date with the text tool, and download.

The PDF is processed in your browser, not uploaded for editing.

Adding the date and your printed name

Use Preview's Text tool (the "A" in a box) to add a date and your name beside the signature. Typed dates are easier to read than handwritten ones.

Common problems

• Preview will not save changes: the PDF may be locked against editing. Check Tools → Show Inspector → Encryption. See PDF permissions explained.
• The signature looks jagged: use the camera method, or draw a larger trackpad signature.
• Form fields lose their contents in another reader: some readers display Preview's annotations differently. Export a flattened copy with File → Export as PDF, or see how to flatten a PDF.
• The recipient wants a certified digital signature: Preview creates a visual electronic signature, not a certificate-based digital signature. See digital signatures vs electronic signatures.

Is a Preview signature legally valid?

For most everyday agreements, yes. Electronic signature laws in the US, UK and EU accept drawn signatures in many contexts. Some documents need a qualified signature, a witness or a notary. See is it legal to sign documents electronically?.

Takeaway

On a Mac, Preview's camera signature is the fastest route to a natural-looking result, and the trackpad is fine in a pinch. For more control or a typed signature, use a browser editor. On Windows, see how to sign a PDF on Windows.