I have never seen a fragrance oil that told you how much to use...I understood that is usually dependent on the product formulation - which will vary greatly from product to product and person to person. And drop sizes vary also - depending on the viscosity of the product, its surface tension, and the size of the dropper. (see? I WAS awake in chemistry class....now and then !)
The only static numbers and percentages that I know of are the IFRA Maximum Use Level given to each product. And this oil is listed as safe at 20% in oils and lotions - which would be way too much in a lotion bar - lol
But yes, it is a very light scent... so great in the bottle... But if I keep adding more and more, eventually it will affect the consistency of the bar. I usually make up a large batch of unscented, then remelt and add scent to small test chunks of 1 oz. Then do the math for larger batches based on that.
Then again - trial and error is a good method , too