What is the weight of the snake? I tend to go below the 10% rule for feeding live. Actually I go by the head size and width of the neck. I have some ball pythons that grew pretty fast and are still young, so they don't really have the neck power to safely take a rat that's 10% of the weight. I also have some older females that were underfed and thin when I got them, but they were older snakes. They could easily take a rat 10% or even a bit bigger. I guess I'd go by the age of the snake too. But to be safe I'd feed at about 5% of the snake's weight. Some people don't feed live rodents above 70-80 grams. You could try feeding a rat crawler just to get him in the mood, then follow up with a bigger frozen thawed or pre killed. I was feeding all live for a bit until one of my snakes got bit pretty bad, now I tend to feed medium and large rats pre killed just to be safe.