When I look at the reputation league for the RPG site on stack-exchange, I can't seem to find my username. How come it's not listed?
Try the month view.
You have have a reputation change during this current week for your name to show on that page or be searchable (subject to caching). As of this posting I'm not in the week view (though I will be when the cache updates), but I am in the month and quarter view which have far more users.