I found that by going in through "All Foods" and then "Poultry" and then "Chicken", I can choose (for example) under "Chicken Breast, with or without bone", the entry called "Roasted, Skin Eaten" which gives a lot of choices for quantity:

1 cup cooked, diced
1 oz boneless cooked
1 oz boneless (raw) yield after cooking

etc. I usually use the "1 oz boneless cooked" and weigh what I'm going to eat.

I've found my $10 scales priceless and have managed to find a way to enter most foods by weight.