Do a google search for HUD Fair Market Rents, include your area (county, city, state, whatever) as well as the year of the loan you are reviewing. The fair market rents is the target you're shooting to be below for inclusion in your CD file.
You don't need to "prove" that the units are inhabited by LMI people. You do need to show that there is a likelyhood that they are, based on population base (geographic tract income levels) as well as any external factors that would lead you to believe this (ie close to a base). Then you use the fair market rents as your guide and show your rents are below those, thus making it affordable. If you're having trouble finding rent rolls, look to the appraisal. It will have rents listed on....probably page 2 or so. Look to actual rents, not suggested market rents.
Be sure to look to purpose of the loan. If the CD deal is affordable rent, it still won't count if the actual purpose won't benefit the market. (IE a land baron taking funds out to remodel his castle)
