by the looks of what people say...VERY carefully
it doesn't look like it takes all that much of this stuff to throw yourself into an opiate overdose.
i'm thinking that maybe dipping the end of a toothpick in it and putting it under your tongue MIGHT give u a low enough dose.
then agian i have NEVER tried any form of fentanyl, and the only opiate i've tried is codiene(yay T-fucking-3s).
so maybe get some other opinions before u try this.