How to sign a PDF on Linux
===========================

First, you need a transparent image of signature, eg as a PNG file. Android
works pretty well for this: you can sign a blank piece of paper, take a
photo, and clean it up. Then can use gimp if necessary to remove background
and make a transparent image.

NOTE: if text import isn't working, need to go in preferences and change input
type (!), see also <https://github.com/xournalpp/xournalpp/issues/2035>.

To edit PDFs, use `xournalpp`, which is a GUI tool packaged in Debian. You
can add text and paste images, then export as PDF.

Via: <https://www.xmodulo.com/add-signature-pdf-document-linux.html>