Suggest Direction Of Use To Apply Fucidin Cream To Penis

Wondering exactly where to apply fucidin cream to my sons penis. It was inflammed last night and I bathed him in an epsom salt bath and the inflammation and the swelling went down a little. Then my doctor prescribed fucidin cream for him. Should I just put it on the tip of his penis where the redness appears, or should I pull the foreskin back (as he is not circumcised) and put it on there?