Verifying signature owner (without verifying the actual document)
No.

An RSA signature is just a single number, encoded in a certain way. The number represents $x^d$, where $x$ is a padded hash of the document and $d$ the private exponent. If you know a public key $(m,e)$, you can calculate $x = (x^d)^e \mod m$, but without a document (or at least its hash) there is nothing to compare it with to verify anything.

The only thing you can check is whether the signature matches the size of the key (e.g. both 2048 bits). If it doesn't, it clearly isn't from that key, but that's it.