In the first pic he looks perfect
, but in the second pic I did think a bit of padding was needed...
BUT, I have no experience of working cockers, and don't see them locally, so I can only compare it to a show, and of course that is not a fair comparison..
You can actually see his ribs in the second pic, and he does narrow significantly behind his ribs, and he appears to have a bony bum...
However, if he is happy, healthy and lively then I don't think it is a huge issue...
Obviously, you as his owner know him best and will be the first to notice if he may be poorly.
Personally I would add something 'wet' to his food, like tripe or naturediet and see if that puts a bit of padding on. If it doesn't then perhaps see the vet to see what they think as failure to put on weight may be significant...
He is absolutely gorgeous - I love the chocolate cockers