Is there a possibility to add a signature in PS as a brush or a standard action?
I wasn't kidding. There was one guy I read about who was suddenly about to lose his house because he'd done something like this with his real full signature on images and articles on his website. A simple whois lookup revealed his name and address from his domain name, so it wasn't difficult for the identity thieves to find out more information about him, and con various organisations into giving them loans and credit in his name.
Easily doable, but don't use your REAL signature.
Read quite a few stories of people doing this then having identities stolen because the bad guys now have a real signature to practise against.