You don't actually have to label soap at all in the US. If you do, you have to do so correctly if you are selling. Do you have to fully correctly label when you are gifting...............we get in to more than 50 shades of grey there.
I agree with green soap. Some people can develop sensitivity to essential oils even after they've used them before with no problems. I list all of the essential oils on my labels. Better to be safe than sorry!
They are considered a fragrance. You can simply call them "fragrance". You can even list some EO's and not list others just by putting "fragrance" along with the names of the EOs you do want labeled. Its a blanket term that is acceptable.
That being said, any time I add EOs to one of my soaps, I list it. It has good and positive ring with customers to see EOs on labels. I wouldn't, not list them if I put them in. However with my room sprays and wax tarts even if they are scented with EOs I just call it fragrance because it greatly simplifies labeling and I don't worry much with those because they are not a body product.