I had a smaller prime rib (about 4 lbs.) so I halved the rub ingredients and it was the right amount to cover it generously. I was not sure why some of the spices are listed twice in different amounts (e.g. celery salt as 2 TBS and 2 tsp) so I just used half of the first amount which seemed to work fine. About halfway through cooking I added baby carrots to the pan and they ended up with a nice herb flavour from the drippings.
I usually cook my prime rib with minimal seasonings (garlic cloves inserted/salt/pepper) to let the meat flavour dominate, but I have to say I prefer this more seasoned version. The rub crusted nicely during the searing phase and the meat was tender and delicious. I wish I had remembered to take a picture before we devoured it! Thanks for a new favourite recipe.