The flint wheel lighting mechanism works just like the flint wheel on a cigarette lighter. A knurled wheel is spun across a flint, which is pressed against it, and throws a spark. The spark ignites propane leaving the burner head.
The flint wheel worked fairly well when all the parts were new, but became increasingly difficult to use as the knurled wheel became smoother from use. The flint, of course, would have to be replaced when it was used up, but the friction on the knurled wheel would wear it down also. As the knurled wheel became smoother over the years, the user would have to spin the knob faster and faster to throw the spark far enough to reach the burner. When parts were available, replacing the knurled wheel made the device work well again. Note: there were left hand and right hand threaded wheels, depending on which side of the burner the flint mechanism sat.
The price of a replacement knurled wheel rose from around $2.00 to close to $35.00 after they were discontinued by the manufacturer and are now nearly impossible to find new. Generally, however, the models of refrigerator that used the flint wheel were models that were also reasonably easy to light with a match (usually from behind). If this is the case with your refrigerator, use the match. If you are in a position where you can't reach the burner with a match, or just want everything to work right, you can try roughing up the knurled wheel and lubricating the shaft to the wheel for easier spinning.