To help you with some idea of normal amounts (though this is based on UK foods, and dogs vary - as mine do!) my two are both fed on Burns Brown rice and lamb or fish. I try to keep both their weights around 9kg. Oliver is active and almost 10 and tends to lose weight quite easily, so he has 100g a day plus a good helping of raw vegetables. Aled is a Blenheim who only has to look at food to put on weight (and has a Grade 3 heart murmur), so his maintenance amount is 60g and if his weight starts going up (when he gets less exercise in bad weather, for example) it's cut to 50g with extra vegetables (and 3 or 4 times a week he has a couple of small low-fat sausages as his training treats). On these amounts they have plenty of energy, good coats and skin and are slim but not too skinny, so the amounts seem to be adequate. Raw vegetables are a good way to help the dogs to feel full without adding calories; mine love cabbage, brussels, carrot, parsnip, raw and frozen peas and beans, squash, asparagus trimmings, broccoli, spinach - almost anything except the onion family is OK for them. They also have half a carrot each as a bedtime treat - it's often not the mealtime food that puts on the weight but the treats in-between! And do weigh your 3/4 of a cup from time to time - it's amazing how the extra biscuits creep in!
Kate, Oliver and Aled