Absolutely, with CRF, don't even bother with any over-the-counter food. Immediately switch to a prescription diet designed for kidney disease like Science Diet K/D or Royal Canin Renal Support. There is nothing else that compares to these diets formulated already with restricted protein and limited phosphorous. Very important.
If won't eat it, ask the vet about trying some Mirtazapine. It can be a very handy once every 48-72 hours appetite stimulant medication.
He also may not want it due to stomach upset. High kidney values can cause ulcers in the stomach. To help, you can start giving some over-the-counter Pepcid A.C. 10mg regular strength antacid. Just a 1/4 tablet of a 10mg Pepcid once to twice a day would work. Confirm with your vet if twice daily indicated based on what is going on.
With concurrent pancreatitis, that is very serious and very sorry to hear about both problems. I don't know if the diagnosis is correct or if proper additional testing was done to verify if there actually is pancreatitis or not. That would typically be a add=on test like a cPL at the vet office or a CPL test sent out to a laboratory. These cost more money. So, vet might be assuming (just a guess).
Nonetheless, have to assume they are right, and if so, pancreatitis can be painful.
So, also talk to the vet about trying a little pain medication called buprenorphine to help out the abdominal pain commonly found with pancreatitis.
Wish I could do more but hope that information helps!