Co-witness refers to the relationship between the optical sight and the AK’s fixed or iron sights. When you co-witness you’re able to align your iron sights in tandem with your red dot optic. Where the red dot locates in the optic (middle or bottom 1/3) is a matter of preference.
The illustration above shows the red dot in a co-witnessed position resting directly above the post. This means that the two sighting systems are zeroed for the same distance and windage. Both the Aimpoint and the Primary Arms optics allow you to co-witness on a Saiga using the RS Regulate mount.