I have a 2 year old entire male Golden Retriever he is a bit fussy with his food although always fit and well, the vet says his optimum weight is 34kg, at his last weigh in he was 33.5 kg but he still looks on the thin side to me, is this normal?

Better to be on the lean side than overweight! ;) When you stroke his sides, can you feel his ribs beneath a thin covering of flesh? If they're very easy to feel he may be too thin - if you have to press hard to feel them he's too fat.

If he's fit and active, he's probably fine. The majority of dogs in this country are overweight, and it shortens their lives.

This is very typical Goldens, perhaps not to be a fussy eater!! :) but to be lean as youngsters. You'll find once he hits 3 or 4 years of age he will start to pile the weight on and you'll have to be careful that he doesn't gain too much. Every single Golden I've ever had (9) have been like this. He doesn't sound all that lean anyway :) I have one (male) who now at 2 years who weighs in at around 27 kgs and he's having to be fed 3 times a day at the moment to not get too skinny.  I'd say at his size he will weigh around 34-35 when fully mature.