What kind of cham do you have?
Montanes drink from water falling on their head and into their mouth, panthers and veileds use their tongues to lick water off leaves and branches, but will also flick their tongues at running water.
A rain dome would benifit a jacksons more since they actually get themselves IN the rain.
But for panthers and veileds, I just use a dripper.
I do have them on a Mistking, but have yet to actually see them drink from it.
I have seen them drink from the dripper though.