Now. I'm not really familiar with many American football signatures. However. I know people who while in America obtained his signature during his time as San Francisco head coach. So just going off the example I've seen of there's. I'd have to say this is not authentic. However. I don't know if his signature has changed since then. And what his standard signature is like. Maybe there's they got signed was slightly different etc. Many factors. So I'd wait for more opinions as I can only go off what I've seen online that have been verified by PSA and that one example I've seen in person. Sorry I couldn't be of more use.