The German tank sights (the ones with the "triangles" as in the screenshot) will never be functional due to the limitations of the engine. IF they were functional, you should choose the ammo type, and thus the "needle" would be either on the PzGr (AP) or SpGr (HE) scale. You would then twist a knob to set the range in 100s of meters (2, 4, 6, 8...) and the vertical position of the triangle would adjust accordingly. Of course, the trick would be to know the proper range
But if you knew the range, you would no longer have to guess (or very painfully and slowly learn) the correct elevation anymore.