There are different supplements you can get.
If you use Repashy I think it can be used daily. Check the bottle/container though to be sure because I have never used it. It is said to be a great Brand.
Herptivite is another multivitamin supplement that should be used one day a week.
Calcium with vitamin D3...
Flukers and Repcal can be used every other feeding. I feed my red eyes nightly and dust with the supplement every other night, but not on the same day as the multivitamin. There are liquid supplements also, which I only use in emergencies.
The absorption of calcium is minimal without vitamin D3. Vitamin D can be made by our bodies and other animals with ultraviolet light. It is also synthetically produced by scientists/pharmacologists as a supplement. Vitamin D3 helps us to absorb calcium and assists in proper use by our bodies for the creation of strong bones and teeth by creating stronger osteocytes (bone cells). Calcium also helps regulate muscular function by assisting with muscular contraction by use of electrolytes and ions passing through the sodium/potassium pump. It's technical, but here is an explanation for those who want to read it.
http://wiki.answers.com/Q/How_is_cal...ium_pump#page1
This is why when our frogs first show signs of calcium deficiency we see symptoms such as twitching, stiffening, and lack of coordination with mobility. The symptoms would actually start with numbness and tingling, but being our little amphibian friends can't tell us they are experiencing such feelings, we usually don't notice until is progresses to the next level.
Tetany (a group of symptoms caused by low blood calcium levels) progress in somewhat of a usual pattern... Numbness, tingling, involuntary twitching, tremors, lack of coordination, stiffness of muscles/joints, decreased contractility of internal organs and alteration of electrolyte flow through organs, seizures, paralysis, death.
Amphibians may end up with Metabolic Bone Disease. It may be stopped if caught early enough, but some damage or disabilities may remain.
Amphibians and reptiles are prone to such deficiencies in captivity for a few different reasons. First, lack of UV light for photosynthesis of vitamin D3. Simply put, no sun light. Second, food. In nature amphibians and reptiles would have a wider range of insects to eat. Most wild insects will feed off of either other insects, or plants. Whether they are eating plants or the insects they're eating is eating plants, they have a wide variety of nice leafy greens to munch on. Some frogs also eat larger prey, containing bones. This may include other amphibians, mice, birds, etc. Natural water run-off in some locations may also have calcium, depending on the rocks/stones within the layers it flows through.
Most of us feed our frogs crickets, which honestly are not the most nutritious insect out there. We use them because they readily available, small, and easy to feed. This is why gut-loading is important, along with the vitamin D and calcium supplements.
Other nutrients and minerals and needed in micro amount for frogs too to keep the organs, muscles, bones and skin healthy and to help regulate these body systems. We and they use even the most minute nutrients or chemicals that can cross over membranes/tissues and nerves and assist in transport of other nutrients or energy to keep our vital functions working. They may be much smaller, but all cells require energy and nutrients to live, function, and maintain good health. Otherwise our body functions are altered or stop....hence ailments and disease process can occur or start. This is why we provide small amounts of multivitamin powder dusting.
The problem with multivitamins in small animals is that we need to be careful with the amounts given. High doses can quickly lead to toxicity in such small creatures. Think about how small human MVI tablets are in comparison to our body mass size. We couldn't possible give our frogs such a tiny pill and how could they produce something so minute with accuracy and of equal dose? That is why we only dust in small amounts. They need the vitamins and minerals, but at tiny dosages. That is the safest way.
Here is a good article about calcium and vitamin D. It refers to humans, but the basic scientific data remains the same.
http://www.health.harvard.edu/newswe...our-health.htm
This is why I supplement my frogs' diets. I have treated tetany in both my starving red eyes rescued from my local pet store and my pacman frog from another local pet store.
I hope this helps. Please forgive my medical terms. I tried to write in English vs. good old Latin med. if you have any questions, post away. Though, I am at work all day tomorrow 12 hrs.