I know this sounds bonkers but before putting in oven, dry the rind thoroughly with a hair dryer full blast for 2-3 minutes. No oil required - just season before placing in oven.
Once meat is cooked, remove the rind completely from the meat. Leave meat in foil to rest and put rind back into oven, turn heat up and bake rind on a baking sheet in top of hot oven until beautiful and crackly.
I have a Rangemaster and follow this procedure using the gas oven. Never fails! 😁