Diaper rash question

My baby girl had a diaper rash that later turned into a yeast infection. I went to her pediatrician and he prescribed Nystatin. He said apply three times a day using desitin In between. I forgot to ask him this question so I’m asking here, When it’s time for her next diaper change, let’s say she peed, am I suppose to wipe the Nystatin off ? And do I rub it into her skin or leave it on the surface?