What kind of sample, like a 100 point one? I need to go look if so!
It comes with a smudger thing (I'm sure the sample probably didn't come with that), but really, fingers work the best, because its warms it up and diffuses better (rather than just pushing it around) IMO.
For cheek bones, I'd look for basically the highest point on your cheek area. The idea is to put it where the sun would hit, and then blend out.
I have the deluxe sample size and use my fingers to blend. I have a chubby face so no prominent cheek bones, but I apply highlighters at the top of each cheek.