Recently I learned that if I add Glycerin to my fondant that it will help it not to crack as much when applying it to a cake. My problem is that all people will say is to add a dollop to the fondant and need it in. How much is a dollop? I don't want to add too much and ruin my fondant. Thanks for any help you can give

I add a tablespoon of glycerin to a batch of fondant. By a batch, I mean when making fondant with 2 bags of marshmallows.

Wilton has a rolled fondant recipe that uses glycerine. 1 TBSP to 2lbs of icing sugar