So how do you find the actual needed string length for a R/D?  Do you measure along the back of the bow following curve or straight line nock to nock.  If it is straight line my string seems right but it still braces at like 1 inch.  Anyone had this problem before?

R/D or not follow along the length (from the tips where the string seats, along the limb curves and handle) of the bow and subtract 3" for longbow, 4" for a recurve. Then twist for your brace height.
Check after a 100 shots for stretching and re-adjust by twisting.
A good habit to always check your brace height before shooting as it effects the performace of the bow and nocking point height.