Remove the butchers twine if it came on it (but save to reattach). Then salt it down all over inside and outside. (Cut the ribs away from the meat a little if it wasn’t already done from the butcher)On a sheet pan, generously salt the prime rib all over and place in the fridge uncovered, overnight to dry out for a crispy crust! The next day move the meat to a roasting pan, ribs side down if you don’t have a rack.
Cut small slits in the roast and insert garlic and rosemary. Rub compound butter all over the meat.
Bake at 500°F for 15 minutes. (Be sure it’s been preheated for at least 10 minutes)
Reduce heat to 325°F and continue baking for 13 minutes per pound, or until desired doneness is reached. Don't open the oven until it's done!