You need to sign a PDF on your iPhone. You open it, look for a sign button, find a confusing menu of markup tools. Or you find signing but the result places signatures awkwardly.
What's actually going wrong
iOS has signature support in Markup, but it's buried. Many apps don't expose signing clearly. And the built-in Markup signature is limited — single signature stored, awkward placement, no signature image support.
The quick fix
Native route: Open the PDF in Files or Mail. Tap Markup (pencil icon). Tap the + button, choose 'Signature'. Sign with finger or stylus. Place on the document. Save.
Flint route: Open Safari, go to Flint's sign PDF. Upload the PDF, sign (draw, type, or upload signature image), place, download. More flexible than Markup, supports stored signatures, and produces consistent results.
If that didn't work
For signatures that need to look professional, use a stylus (Apple Pencil or third-party) rather than finger. Drawing in Markup or Flint with a stylus produces clean signatures.
For frequently-signed documents, save your signature in Flint or store an image of your signature in Photos for reuse.
Prevent it next time
Create a clean signature once (drawn or uploaded image), store it, reuse. Use Flint for cleaner signature placement than iOS Markup offers.
FAQ
Can I sign with my finger?
Yes, but results vary. Stylus or Apple Pencil produces cleaner signatures. For document-quality output, a saved signature image (drawn on a tablet, photographed, or generated typed) often beats finger-drawn.
Does iPhone signature look legitimate?
Yes, electronic signatures from iOS Markup are legally valid in most jurisdictions. The visible appearance might be rougher than desktop signatures but legal status is the same.
Can I use multiple signatures?
iOS Markup supports multiple stored signatures. Tap + > Signature > add new. Useful if you sign with different names or initials.
Why is my signature appearing too small?
Default placement is small. Tap and drag the handles to resize after placing. Both Markup and Flint support post-placement resizing.
iPhone signing works. Flint's sign tool gives cleaner results than native Markup if you need it.