Yeah, like Tommy said, depending on your tolerance you may have to cut the patch into equal size pieces so you can use them safely. And since you said you've never had fent before, when you're cheeking the patch, make sure to not let it fold or anything, and you don't want to chew on it at all. Just kind of let it chill between your gums and your cheek. & try not to swallow too much, which I know is easier said then done, cause sometimes a lot of saliva builds up when trying to use something bucally. At least, that's what happens to me, lol.
But also, depending on your tolerance, fentanyl might not even be for you. But we'd need to know your tolerance before giving you anymore really sound advice...