Generously sprinkle the cavity of the turkey with kosher salt. Loosen the turkey skin from the breast by placing your hand in between the skin and the breast, gently lifting the skin away. Try to loosen the skin as far down as you can go, to the thigh and over the drumstick. Place one (tablespoon) square in between the skin and the meat of the turkey in the following places: each drumstick area, each thigh area, and each breast. Place the remaining two squares of butter in the turkey cavity.