Another suggestion, I might be wrong though.
If you just put Bitcoin address or PGP key, it is easy to impose another person. A signed message is better.
Is exposing your bitcoin address is risk??
Nope, merely exposing your Bitcoin address is not a risk, unless you want to remain 100% anonymous on the Internet.
You can create an address specifically for this if you want to be that anonymous. And NEVER use it for anything else!