I have a scanned copy of my written signature and I need to apply it to some documents in the signature block.  I used to do this on Windows all the time but I now have only Linux. Is this possible?  How can I add a signature image to a PDF file in Linux (Gnome 3)?
How can I add a signature .png to a PDF in Linux?
pdf;evince
Using Xournal you can annotate PDFs and add custom images (e.g. a transparent PNG). Although it is used for taking freehand notes and drawing, it can also annotate PDFs.On Ubuntu:Install Xournal through the Ubuntu Software CenterOpen XournalSelect Annotate PDF from the File menu and select your PDF file to be signed.Click the Image button in the toolbar (it looks like a silhouette of a person).Select a PNG image of your signature.Resize and position the image on the PDF.Select Export to PDF from the File menu.More info at http://www.howtogeek.com/215485/sign-pdf-documents-without-printing-and-scanning-them-from-any-device/