That depends on just what you mean by "RP".
All messages not sent using the "Out-of-Character" message type are supposed to be sent from the perspective of your character, not you. But that doesn't mean that every message has to be full of flowery speech and fancy stuff. It's perfectly acceptable to speak relatively plainly. The only thing to watch out for is if you're on Dwilight, you are expected to adhere to the
Serious Medieval Atmosphere, which, in this context, basically means "talk like a noble, not a commoner or a 21st century person at a computer, and use people's appropriate titles when you address them."
If you want to introduce yourself OOCly, that's also more than acceptable. Just do so with a message sent with the "Out-of-Character" message type, and you should also have your character introduce himself IC once you feel comfortable doing so.
