Is it possible to add a signature e.g. from PDF files or from JPEG images instead of using a web cam? The problem is that I don't have a web cam and I would like to use this feature in spite of that.
It appears that at present, that isn't an option. When I created a signature file using the FaceTime camera, I see that first of all, there is no unencrypted graphic file created by Preview. Preview did a new key in Keychain titled "Preview signature privacy", suggesting that the signature files go directly from Preview's camera interface to an encrypted file. There isn't a supported way to add a graphic as a signature, and the encryption makes it difficult to bypass the approved new signature process.