I am currently experimenting with lotion bars, and they are turning out beautifully.
My question is this - I have made only unscented bars so far. I have purchased some EOs that have therapeutic qualities, such as German chamomile, heliochrysum,etc...

But I can't find any guidance on how much to use of each to get a beneficial effect. Most advice I read is about FOs, but with therapeutic EOs, I would think there would have to be a minimum amount/percentage to get the proper benefit.

I have done a lot of web searches, but not much luck so far.
Thanks in advance for any help or tips you can offer!!

I would recommend that you follow your nose. As long as the purchaser can detect the EO with the theraputic values, you are good to go.

If any EO has the properties that you are after, then we are just discussing how much is enough.
This is now a discussion of depending on what you are trying to achieve/cure/fix/effect; and this can be different to anyone who may buy your product.

If it was CP soap (which I do have some experience) I would add no less then .3 of an ounce to not more then 1 ounce per pound of soap. So, depending on the weight of your lotion bars, you may go from my suggestion.
Now, .3 would be for a very strong EO, like Cinnamon/Rosemary/Peppermint, and I would an whole ounce of most citruses like lime/orange/lemon; the citruses tend to be fleeting. Most any other EOs will fall somewhere between these amounts, and rarely outside of these amounts.

If you have a specific EO in mind, shoot me an E mail thru this site (hopefully, I will get it), and I will suggest amounts if need be. (There isn't much traffic for me to come here often, although I do visit other forums here).

Good luck!