I just saw this photo at Bateman’s in the UK. Paul’s signature is the only visible signature the others are very difficult to see. Look on the bodies for John and George and to the left of Ringo’s foot. As you really can’t see the others how does the Paul signature look?
Besides Paul not looking right to me, it does not look like an original photo. It looks like a digital copy. Here's a comparison to the one you're asking about and the original Robert Whitaker photo:
I saw that one, too. Paul might have been done by Neil Aspinall. In any case, it wasn't done by Paul. Ringo looks very unusual. Lennon might be an Aspinall, and George is so light as to not make me care if it's real since the rest aren't. It's an interesting find, but not one that I recommend you put any money toward.