I am replacing the seal on my toilet and the subfloor is uneven around the closet flange. The toilet was originally placed on a seam in the subflooring--very small bathroom only place that the toilet would fit-I guess. What do I do know? Rubber shims? Is that going to work. I am replacing the seal because the toilet was rocking. I have a plywood subfloor with a linoleum floor.
Thank you.

Level toilet with shims. Use lead, copper of plastic shims. Look in tile department of home center and purchase little wedges for spacing wall tiles. Level toilet with shims. Mark location of shims. Remove toilet and tack shims in place with small, galvanized finish nails or silicone shims in place. Reset toilet.

Thank you for a very quick response. I just bought some plastic shims and will shim it up. Thank you.