Remove any of the innards left in the chicken, rinse thoroughly and sprinkle with a little salt
Chop the rosemary and mix it in the butter
Cut the orange in half and squeeze a little juice in the butter
Put the butter all over the top of the chicken (I realize this is a little extreme, you can use less butter if you care about your health and weight)
Put the orange in the chicken cavity and roast in a skillet or roasting pan in a preheated 425 degree oven until a meat thermometer reaches 165 degrees (about an hour to an hour and a half)