http://www.atiracing.com/instructions/Super-Damper.pdf
You definitely do NOT want the balancer to be larger than the crank snout. It needs to be a press fit and once it is within the specs ATI recommends it will go on and off without any drama..
Press should be just under .001 meaning the balancer is smaller ID than the crank snouts OD by that amount.
A loose fit or slip fit balancer defeats the purpose and can cause broken parts and the crank and balancer will have metal fretting on their mating surfaces....