You are correct, all the Krikit series are v-belt gauges including the Krikit II PN 91132 (which is the one you need). They are not designed for a flat timing type belt such as our Spyder's drive belt. I am assuming this is because the Krikit is unable to give an acurate tension measurement in lbs., KGs., etc., for a flat drive belt.
However, this is not really necessary as the Krikit gives a consistant, reliable, repeatable reading which means it is relatively accurate (though probably not scale reading accurate).
I don't mean to confuse here but all we need is gauge that will tell us if our belts are within spec. Who cares how it accomplishes this task?
Let's say, for example, that we need our belt tension set at 100 lbs. Let's also say that when our belt is set properly at 100 lbs. the Krikit reads 180 lbs. As long as we always get a reading of 180 lbs. from the Krikit when the belt is correctly tensioned at 100 lbs., what difference does it make that the scale reading given by the Krikit is incorrect?
It doesn't! And that is the beauty of the whole concept of using a $20 gauge to do the job of a $300 gauge. We use the $300 gauge for a reference baseline and corrilate this to the Krikit and we're set!
We just need to get that magic number.