I think theorethically you should use a bit which is larger than the core diameter, but smaller than the extended size caused by the small ribs pressed to the surface of th bushing.
In my case the core diameter was a bit less than 11 mm, so only the small ribs cut into the wood. At the case of the 7 mm drill at the bridge, the difference was less, about 0.2mm, and I was able to press the bushing in with the end of the rubber mallet. I am well over 100kgs, so i suppose somebody else with less weight might use blows with the rubber hammer.