^ This. You would use notepad or some other text editor to compose your message, and then after your message, paste your PGP key. Then select ALL of that text (including your PGP key!) and encrypt the ENTIRE thing to the vendor's PGP key. Then you'll have it all in a block of encrypted text which you can then copy and paste into the SR message field to send to the vendor. Since you're encrypting it to their key, they will be able to decrypt your message even without your key (as long as you do not sign the message) ... so they'll decrypt it and then they'll be able to import your PGP key from your decrypted message.