Since version 3.15, we've added the handling of graphical (not-graphometric and not-certified) signature for sign form fields.
Note: the added signature might not be rendered using other readers like (Acrobat desktop version) as it's handled via setIcon, to disable this feature modify Global.sEnableGraphicalSignature.
It can be rendered correctly using: Xodo(PDF tron), Foxit, MuPDF, Acrobat Andrid app
For the KB, these refers to variables: yourSignPage -> the page index where you need to add the signature
yourSignatureBitmap -> the signature bitmap