Hi!
Because oil is so high in calories, I just use the total amount and divide it up by serving. So, if I use 1 Tablespoon of olive oil in the pan to cook 6 chicken breasts, I count 16 fat calories added to each chicken breast. That really isn't enough to worry about in the short term, and I think a lot of the oil gets left in the pan--but I'd rather estimate high with fats.
Do whatever seems most accurate to you and easiest to keep track of.
Jay