standard reverse blades only have blades going the reverse direction on the bottom 1". So the right way has most of the teeth pointing down. I sometimes run a blade across my finger or jeans to see which way it catches, the way it catches should be the downward stroke in the saw.
If you have blades that have reverse teeth throughout the blade (like a fd-ur) most of those have some sort of dent in the top or bottom of the blade, check your directions for details.