Add a Signature Image to a PDF on iPhone

Step by step

01
Choose the signature photo
Create a signature and load an existing picture from Photos, or take a new scan of the paper.
PDF SIGN & SCAN / 01
02
Remove the white background
Check the After preview. Adjust Paper Cleanup until only the ink remains without breaking thin strokes.
PDF SIGN & SCAN / 02
03
Place the clean signature
Open the PDF, tap Sign, choose the saved result, then drag and pinch it into position.
PDF SIGN & SCAN / 03
04
Export the PDF
Tap Send to create and share a flattened signed copy.
PDF SIGN & SCAN / 04

Use a sharp photo with dark ink and even light.
Crop around the full signature, including long first or last strokes.
Keep signature images private; the visible handwriting can be copied like any other image.

Can I use a signature image already in Photos?

Yes. Load it while creating a signature and use the same paper-cleanup controls as a camera scan.

Why does a white box appear around some signatures?

The paper is still part of the image. Clean the background before placing the signature so the PDF shows only the ink.