I just did a search on 'rooting hormone' and found 51 hits in the forum about this topic, so you'll find more info there that I can give you.

In short, some have tried it with success. It has never worked for me, where as Superthrive has done wonders for improved orchid roots for me. But it depends upon what orchids you're trying to propagate, too. Orchids aren't like a lot of other plants in that way. If you took a 10 pb plant, and divided it into 10 individual pbs, you might get 10 plants out of it, but it will be a number of years before you got anything to bloom. Orchids use the older pbs as food to support new growth.

I'm also trying to say that orchids just don't propagate like shrub cuttings- in general you can't just cut off pieces and expect that each will readily grow a new plant. Some types lend themselves more to this, but again not recommended.

I think the actual 'hormones' are secondary to the anti-fungal agents in most rooting powders. If your cutting will form roots naturally, the powder can help keep it from rotting while it does so.
Some people swear by "keiki paste" but I can't offer an opinion on that, never tried it.
Regards - Nancy

I just tried propagating an epidendrum that had several keikis on its stalks. Hope it works. They're not dead yet at least!

Orchids, unlike some shrubs and tree or plants like begonias, won't root from a simple leaf cutting or a cut stem or psuedobulb even with the help of rooting hormone powder or paste. Most orchids have a node, like phalies and dendrobiums that keiki paste can be applied to induce roots. Cattleyas and other rhizome type orchids will have several eyes at the base of the pseudobulb. I haven't tried applying hormone paste on the eye, but it couldn't hurt. A cattleya has usually two main eyes, and two secondary eyes.