I would recommend against supplementing whole rodent prey.
The reason calcium supplements are provided (when they are indicated) is because herps require a balanced calcium and phosphorus intake to avoid elevated blood plasma levels of either; an imbalance throws the metabolic checks and balances into a tailspin. The ideal Ca/P ratio of reptile foods is understood to be 1.5/1. Rats are already 1.77/1; increasing the calcium is counterproductive (a person could use a CaPO4 based supplement, but in the absence of diagnosed need this would simply put more metabolic pressure on the animal to excrete the extra minerals; excess blood Ca and P are actively passed back into the digestive tract and excreted with stool). Calcium demand in a convalescing animal might be presumed to be minimal, anyway, since replacement of muscle mass and fat stores will probably be taking place much more than bone mass increase, giving yet another reason not to supplement Ca.
Sometimes the fact that younger rodents contain less Ca per unit of mass than do adult rodents is taken as evidence that those animals are calcium deficient as prey items. But since it is the ratio of Ca to P that is the relevant metric (and since there is no data on the P content of neonate rodents that I've been able to uncover, and in absence of a reason to think that the Ca/P ratio changes according to rodent age), it doesn't follow that supplementation is necessary.
Further, there's no reason to think that the amount of Vitamin A or D is insufficient in whole rodent prey (in fact, the amount of Vit A in adult rats and mice is thought to be right around overdose levels *), so increasing those levels isn't useful and runs the risk of hypervitaminosis. (Whether dosing B vitamins in a convalescent animal is a separate question, one that's almost certainly answered in the positive, but I don't know the dosing protocols for herps at all, and would recommend checking with an exotics vet for details).
Supplementation is quite necessary for insectivores, only since captive raised insect prey is well established to be deficient in Vit A and D, and has a very poor Ca/P ratio. This doesn't translate into the need for supplementation in whole-prey carnivores, though (and herbivores should get a somewhat different supplement mix because the deficiencies in their diet are different).
A bit of a tangent from the point of this thread, but a useful one I hope.
*
https://nagonline.net/wp-content/upl...nal02May29.pdf