Since line WS and line KV are parallel, any line that intersects them, such as line RT, will form alternate interior angles that are congruent. This means that the angle formed by line RT and line WS on one side of the intersection will be equal to the angle formed by line RT and line KV on the other side of the intersection.
Therefore, the relationship between line RT and line WS is that they form congruent alternate interior angles. This relationship holds true regardless of where line RT intersects line WS.
One reason to support this answer is the fact that parallel lines have corresponding angles that are congruent. In this case, line RT and line KV form corresponding angles with line WS, which means that any angle formed by line RT and line WS will be congruent to the corresponding angle formed by line KV and line WS. This, in turn, means that the angles formed by line RT and line WS are congruent to the angles formed by line RT and line KV.