It's been a while since I've played around with reactive-banana (or anything else that pushes the type system so much), but I think the type signature should be something more like
start :: (forall t. RF.Frameworks t => R.Moment t ()) -> IO ()
(i.e. You need to add parentheses in the right places.)
You'll need {-# LANGUAGE RankNTypes #-}
as well.