When I do roast chicken, I mix butter, garlic and herbs like thyme and rosemary and then squeeze it up inbetween the breast and the skin, you have to get your hand right in between. When I have done that I rub the skin with the remainder of butter and salt and pepper.
I use olive oil butter.
The skin always comes out brown and crispy and full of flavour, the breast is never dry, the meat just falls off the bone.