This was my first time using RBL Teal, a polish loved by many. It applied flawlessly, and if my memory serves me, I think I did just one coat of it!
I put a coat of $OPI Club Scene Queen over top.
Club Scene Queen is a really shimmery, pretty polish that is rather sheer and methinks, just perfect for putting on top of lots of different colors!
My guess is that you could get a decent opacity with Club Scene Queen by doing three to four coats of it by itself. I have a feeling that the over all color would probably look a little smokier and less intensely blue/teal on its own.