It's good to follow the recommended daily amounts for each dog food. But it's also good to check their weight by feeling their body. They should have a waist and you should be able to feel a little bit of their ribs. If their ribs and waist is too pronounce, they're underweight and maybe need more food. If you can't see their waist when you bathe them, they're overweight; you need to make sure they get enough daily exercise and/or feed them less. The shape of their body is a better indicator of what's 'normal' than their weight on the scale.
