Not all prism scopes are designed to be paired with a red dot sight. In general, only the most robust military prism scopes can be combined with a red dot sight using an appropriate mount.
These prism scopes feature a 4x magnification – if the magnification was any lower, pairing the prism scope with a red dot sight would not be rational.
The prism scopes that can be paired with a red dot sight are:
Elcan Specter DR 1/4x32,
Elcan Specter DR 1.5/6x42,
SUSAT, and a few others.
The combination of the two allows for quick target acquisition at close range and extreme close range.