You added this to Kdenlive/Manual/Effects/Alpha manipulation/Rotoscoping:
How to draw the region in Kdenlive? The region is drawn by adding nodes along your region. These act as edges for your rotoscope, and there is a line between each node. The line between to by creating a Bézier_curve on the frame.
The last sentence makes no sense to me. It seems that parts of the sentence is missing.