Yes if the PTRD penetrates into the crew compartment of a vehicle it will kill anything in its way, further more after it penetrates it will have reduced energy and may start bouncing around inside the compartment causing more casualties.
The main use of the PTRD is to disable vulnerable components of a vehicles (sights, tracks, engine etc..) or cause injury to its crew, much like all other AT weapons of WW2. Total destruction of a tank rarely happened, the crew was either injured or killed or some important part of the tank is damaged leading to it being abandoned.
This is a defining unrealism in RO where you must totally destroy a vehicle to knock it out, you cannot kill crew or disable anything other than locomotion systems.