what size do i feed my bp?

my new male BP 09 pastel was not eating but he finally ate a live mouse hopper i tried to feed him a frozen rat pup but he looked afraid of it so what do u guys say? i weighed
him and it says 9 ounces and i got feeding time again friday i rele don't wanna do live again!!

the breeder said he does live and frozen mostly frozen tho

I feed mouse hoppers to brand new 50-60 gram hatchlings.
9 ounces is 255 grams, he could easily eat a rat pup if not a weanling.
If he is eating live and you want him eating frozen then I suggest getting him eating well on live, then skip a week and try F/T again, he will be hungrier and hopefully take it with glee.
Temperature of the F/T is very important, I used a hair dryer when I fed F/T to a friends collection. Try to heat the head area to 86 degrees and then offer it.
Think of it as fishing for snakes ;)
Dangle dangle dangle.
Pull it away slowly, then bring it back closer, then away again. It takes time, patience, and learning what triggers your snake to take it.

Some people also use the bag trick, laying the warmed mouse/rat in a bag with the snake, in it's home.
Or you can add mouse bedding to the bag with the mouse and leave it in his cage for him to smell out.
Leave him be, covering the cage also works for some.

I prefer live feedings myself, but understand how some people feel about that :P

I believe 10-15 % body weight is a good rule of thumb.

The best advice Ive gotten is to find the thickest part of the snake. Thats how big around the food should be