For my PKCS signing certificate I use the current Firefox user certificate store.
First try:
In the Tools-menu I click on “Digitally Sign…”. In the window that opens, I click OK.
Now I’m being asked for a password. But no password works.
Second try:
In the Tools-menu I click on “Digitally Sign…”. In the window that opens, I first(!) click on the name of the certificate and then on OK.
Now I can sign my PDF document.
If there’s only one certificate, it’s not obvious that you have to select that one as well. Could you provide some guidance on this?
Best regards, JR.
PS.: Someone here has the same problem:
