rubberband2
That is a great pic.... It supports directional stability w/o Rudder, but it appears that the Fin is mostly present. The Rudder and the Vertical Stabilizer are responsible for two different aspects of flight.
The Rudder is basically a trimming device, the VS provides directional stability. It can be said, therefore, that the Rudder's task is the opposite of the VS, it stabilizes Yaw, in the turn, or establishes a crab for offset.
An a/c can fly quite well without the Rudder, as your pic shows. An a/c is not airworthy w/o the Fin.