i'm 5,10 and when i first got my bike it had been lowered pretty much as low as it would go and i still couldn't really stand with two feet flat on the floor.
I've had the suspension properly set up now and i'm tip toeing all the time now. Pain in the arse when your going through town by fook it's worth it for the handling compared to what it used to be.
My advice is get used to it. You'll regret messing about with it if you change it..
But if you really feel the need to, on the RSVR with the sachs suspension you need to take the shock out of the bike and adjust the bolt at the bottom. Do'nt get it confused with the rebound, You can also lower it by adjusting the spring.... You'll regret it though