Ferrets are pure carnivores and really live on protein and fat, (they don't 'do' carbohydrate). Whole prey diets are popular, plus now the specialist pellets, one issue with complete diets is the quantity of plant protein used in the formulation. Using dog diets may increase the plant material.
As to calcium/D3, we have no specialist info on ferret requirements. They are likely to need a Ca:P ratio of 1.2:1-1.4:1 like dogs. On a raw diet this means whole prey not fillets.
A hob may weight 1-2kg and a jill 0.6-1.0kg.
Regarding supplementation. NRC data gives the dog as needing approx 22IU/kg body weight, the cat is higher.
One pinch of Nutrobal is approx: 15 IU D3 and 20mg calcium (it will also provide 50 IU of vit A and 2IU vit E among other things). The D3 we use has higher bioactivity than simple vit D.
Practically then I would suggest that three times a week for growing animals a small pinch of Nutrobal, and perhaps increase the calcium further using calcium lactate either again a pinch on food (about 13-15mg calcium) or at the standard dose in drinking water. If you use the food route you could save money by using a pinch of calcium carbonate instead 40mg per pinch (our Calci-Dust).