How long have you been on testosterone? Have you started yet? Mine didn't quite jumpstart until around 13 months. I had some growing before then but nothing substantial like now.
Facial hair growth really depends on genetics. Look at the men in your family and see what their hair is like. If they're Sasquatches chances are you will be too. If they're hairless then chances are you will be too. But everyone is different and you could possibly be the diamond in the ruff.
In my studies I've noticed a few ethnicities having strong beard genes i.e Northern European, Italian, Indian, and Arabic backgrounds and some having little to no hair growth i.e Asian backgrounds and Native American backgrounds. But that doesn't necessarily mean your family being asian or native american causes bad facial hair growth. Look at Hayao Miyazaki for example. That's a great beard!!
I wouldn't recommend putting anything on your face as the skin there is a hell of a lot more sensitive than the top of your head. But, If you're dying for that beard I'd recommend Biotin, Certain types of Maca, Hair, Skin and Nails supplements (Biotin can be found in these), and willpower.
If you really wanna try Minoxidil I'd have a look at this link first
http://jefffsbeardboard.yuku.com/topic/23391/Minoxidil-Summary-and-Experiences#.VYHrR_lVjZARemember that it can take 4 - 6 years on testosterone for your full beard potential to shine!! Good luck and happy bearding!