Yes, they sound like fine fat babies! Mama's doing great. You shouldn't need to supplement them unless something bad happens. You can use the KMR to mix with some canned food when they start to eat solids.
If the mama cat likes the KMR, you can give her a bit, but it's not necessary if she's healthy and well-fed. It does provide extra calories and nutrients so if she starts to look a little peaked, you can add it to her food. The biggest stress on the mama is when the kittens are about 3-4 weeks old---they need to eat so much, and most aren't on solids yet, so it gets to be a major strain on poor Mama! So it's always an option if she needs some more calories.
If the mama cat likes the KMR, you can give her a bit, but it's not necessary if she's healthy and well-fed. It does provide extra calories and nutrients so if she starts to look a little peaked, you can add it to her food. The biggest stress on the mama is when the kittens are about 3-4 weeks old---they need to eat so much, and most aren't on solids yet, so it gets to be a major strain on poor Mama! So it's always an option if she needs some more calories.