Into the buttock with an insulin syringe. You can find out about such details by simply using Google and coming across tips from transgender people on forums, including reddit.
Estradiol solved this problem only partially. I tried to give up Bicalutamide, but then the oily skin partially returned. Of course, it doesn't come close to testosterone-based oiliness, but I love dry skin.
As far as I remember, this is a rare individual reaction. I'm not worried about it. Perhaps I should be more careful if I decide to take it for life.