Ok so I'm torn on this one, in the way that...
I do want to support the RP community, but on the other hand cluttering the chat will make it hard to distinguish important information.
People suggest Echo, I think that is wrong because then you might as well play a solo game. You are RPing in an MMO to find other people to RP with I guess and I am sure this is a great way to do that.
I have two suggestions, the first being simple and I think most accepted by all.
It's simple, just use the macro the FIRST time you use the skill in an instance and never again. People saw the text, it was fun, don't overdo it or it loses it's charm.
The other suggestion is if you absolutely want to keep using the macro then I suggest using /say for the macro as that makes it very easy to weed out from party and alliance chat. It is also a lot less noticed by people, heck even NPCs use this channel to spam so by all means spam ahead.