Question about public key encryption

does anyone have the experience about public key encryption with ruby? I
know how to use the module OpenSSL::PKey::RSA to create public/private
key pair and encrypt/decrypt with the key pair. however, if I only know
other guy's public key, is there any module or method to encrypt data
with the guy's public key?

You could try reading the answers which were given to you before. e.g.