I stick to my 0.5 oz PPO ratio on the EOs I use. Some use 1-3% of the weight of the diluted soap. YMMV based on your EO/FO, and how strong you like your scents. If in doubt, see if the vendor has a recommended amount to use on their website.
I use anywhere from .3% to 1% per pound of my diluted soap's weight, depending on the scent (I use FOs). I've found that I can get by with a whole lot less scent in my liquid soap than I need in my bar soap.
Ah, seconds too late, dear IL - I just put my unscented LS in to the dispenser with some Nag Champa scent at 5% of the diluted weight! I have to say, the scent is certainly staying. Any time anyone here asks about getting a scent to stay on the body after use, I'll suggest a liquid soap at 5% and it will be like wearing a perfume!
thanks all...I added fragrance this afternoon. sort of went by smell. Worked out great! The rosemary mint (FO) cause the soap to get white (cloudy and like a pearl color)- but the color I think is beautiful. So, exciting...My favorite was the Lavender Peppermint. Used 1.5 oz Lavender with 0.5oz Peppermint added to 24oz diluted soap. The soap remained crystal clear. I also fragranced another soap with mango tango which caused the soap to get a bit cloudy but its still beautiful in my opinion.
I am not one of those "soap must be crystal clear!" types. It is nice to see a liquid soap with some cloudiness/milkiness. I really hate that I can't get the solids to stay suspended in my liquid lard soap.
The other good thing about liquid soap is that you can use a drop or two of the liquid colorant intended for MP to color a whole batch. I gave out bottles of red liquid soap and green liquid soap last Christmas. Scented the red with spice EOs, and the green with wintergreen EO in some and peppermint EO in the others. Very festive.