hi...that of course will depend on whether its canned or dry food you are feeding. it mostly depends on calories rather than amount and every food has a different calorie ratio. I have been looking for a site I had saved that gave this info but so far haven't been able to locate it...sorry.
I will keep looking, but I am sending you this one site that has lots of info regarding 'what it costs to feed a cat' I haven't read thru it well but I did see towards the end it does give some info on 'recommended daily amounts' I hope you can read thru it and find the help you are looking for....I will keep searching for my chart too..
the Vet is right in saying to feed small portions and often, I haven't had a kitten for years...but I do know even my one cat who is on canned food wil only eat 2oz at a feeding...but he eats 3-4x a day min. he's a 11lb. boy and just a healthy weight.
IMO if its canned food feed a good tablespoon or two, if he walks away he's full otherwise if he's asking for more than add another tbsp.
so much depends on the calorie intake as I mentioned AND if its high quality GRAIN FREE food and NO By products they will eat less than if its a crappy brand...so you'll need to experiment somewhat....hope this helps
http://catcentric.org/nutrition-and-food/raw-feeding/how-much-does-it-cost-to-feed-my-cat-or-i-can-afford-to-feed-commercial-raw/
heres more real good info on diets....
http://consciouscat.net/2012/03/22/the-best-food-for-your-cat/
Thank you so much! He's on PURINA Veterinary Diet Feline NF Renal Function which is a pate like food, not dry.