Toilets, Sinks, Showers, Tubs and Disposals - toilet flange help

I had to reinstall the toilet after new tile had been laid. Problem is that when the previous installation of ceramic tile was done, the toilet flange was made to rest on the tile. I had linoleum installed(old tile removed) and now I have a 1/4 gap under the toilet flange. The problem is that with the toilet re-installed the toilet rocks back and forth. Do I have to shim the front part of the toilet? Or is there a way to lower the flange to be flush with the linoleum? Thanks for any help.

You really need the flange supported all the way around. Perhaps cutting a piece of 1/4" plywood to fit under the flange and then cut it in half to slide it under the flange before screwing it to the flange and floor. If there is any movement, the flange will eventually leak and probably break. Good luck.