No correlation? Nah, there's some. And from what I've seen, your RHP rating will be something like 100 to 200 points higher than than your USCF rating, depending on how much you use opening theory in your RHP games. You obviously can't do that OTB. USCF ratings have gone down - not up since the 1990s. It's a little shocking and humbling. You can be 1800 here, and then get thrashed by a 1600+ rated player OTB within the U.S.
So fair warning!
I just played a USCF Master, friend of mine, over the Labor Day weekend. We were playing blitz at 5 to 1 or 6 to 2 time odds. Out of six games, I won just one - on time. Some ended very early. I have a 1900 rating here. OTB, master means master. I must add, though, that his Fide rating would be under 2200!