I have small breed bitch that is coming up to 2 weeks post whelping and she's not eating much at all. 
I'm worried that she is approaching the high production time with low intake. 
My concern is greater as another bitch went down with eclampsia who ate well.
Fed on good puppy kibble with tripe, eggs, fish. 
Not my first litters but been used to lager high appetite breeds
Would you give ge lactating bitch calcium supplement?

The bottom line would be whether the puppies are quiet, content, and gaining weight daily.   How many puppies does she have - with our first litter (which wasn't the easiest but probably because I was doing it for the first time, with no help other than my vet), there were only 2 puppies, one DOA.    I panicked because mum wasn't eating much at all (and yes, she'd been checked by my vet, who had to deliver the DOA puppy).   However, clearly she had more than enough milk to provide for her singleton puppy who had the run of the milk bar.   She didn't eat much and because all the books say they should, I was worried.   Nature does know best though, so provided your litter is thriving, and mum isn't actually sick, I'd not think about giving extra calcium without being advised to by a professional.

http://www.petmd.com/dog/conditions/reproductive/c_dg_eclampsia

Nursing bitches DO NOT need 'puppy food'.   They need the same good quality diet they should have been on before being mated.   Puppy food is for ....... puppies (to eat).  By all means add some extra protein to her food, but feeding puppy food isn't needed.   The main thing about puppy food, apart from the ingredients being what A PUPPY needs, is the fact it's made so puppies can eat it easily.   Size of kibble and consistency.