There is no "address" for RSBot. RSBot (and GSBot as well) run on mIRC which u can download here. Once u have mIRC, type the server irc.freedomirc.net and port number 6667. When asked for the channel, simply type in #rsarena (#battlearena for GSBot).
I don't think RSBot is completed yet as some testing and programming is still going on. I wouldn't worry about looking for some one to battle when it is finished, though, as people will FLOCK to it.
Anyway, for more info on RSBot or GSBot visit the Online Pokemon Battling Forum on TPM.