I prefer to use Fluidmaster's wax free toilet gasket:

http://www.fluidmaster.com/pdfs/7500_instructions.pdf

Or a similar type made by Fernco:

http://www.fernco.com/plumbing/wax-free-toilet-seal

I gave up using wax rings years ago once these became available.

And if you're cheap like I am, consider the fact they are re-usable...:)

I like those. But I'm still not sure they will work, as the closet flange itself is below the tiled floor. I tried a rubber gasket, but it's not thick enough. And the reno kit left the w.c. wobbling 3/4" above the floor. In the end--just finished--I used one of the reno kit rubber spacers and the rubber gasket. Voila!

Now, to patch the ceiling I didn't have to break in the first place. :(