How to digitally sign a PDF with a X.509 certificate I'm looking for a tool to digitally sign PDFs with the private key of my X.509 certificate.

macOS' Preview app only copy a scan of my handwritten signature into a pdf...
PortableSigner is a tool to digitally sign PDFs with X.509 certificates.

It's a Java app so the installation of a compatible JRE is required (according to the website: 1.6 and 1.7).