Fractionated coconut oil contains smaller-chain fatty acids that are nice in lotions and other skin care products, but aren't so good for soap. T
Soap made that contains a high % of FCO will be harsh and stripping to the skin due to these fatty acids. Not a good thing for soap. That's why you're not finding ready-made recipes for soap that call for FCO.
If you're determined to use it, however, just substitute FCO for the regular coconut oil in any recipe. You MUST use a soap recipe c@lculator to recalculate the correct amount of NaOH for the change, because FCO requires more NaOH to saponify than regular coconut oil needs.
Even if you do find a ready-made recipe, I recommend you double check it using a soap recipe c@lculator to make sure the NaOH weight for your recipe is correct. Even the best soap makers make mistakes. I's wise to never assume any recipe is okay, just because someone publishes it on the internet or in a book