Using Microsoft SIDH library for messages signing
SIDH is a key exchange algorithm, not a digital signature algorithm. The way SIDH works is each side generates a private, random value along with a corresponding public value. The public values are exchanged, and from this, a shared secret can be mutually calculated. No signing is involved.

If you need a post-quantum signature algorithm, you would want to look at something like SPHINCS. You can also use a classical, non-PQ signing algorithm if your threat model allows it.