I'm agreeing with Dennis... the correct way is to have the flange sit on top of the finished floor... if the tile butts to the flange, the cheat to get around it may be to install two wax rings rather than a single one. All depends on stability of the subfloor, relative heights, etc.
You may not have the ability to raise the flange if it's in poured concrete though?
Oddly when we moved in here, I got reminded about how they used to do things. All our major waste plumbing is torch-brazed thick wall copper here... and the toilets are set in an entire bed of plumbers' putty. I'm used to plastic flanges into ABS pipes (or in my parent's place - all cast!)
Bren R.
