The diagonals of a rhombus are perpendicular and bisect each other.
Since the lengths of the diagonals are 16 and 30, they divide the rhombus into 4 congruent right triangles each with legs 8 and 15; each side of the rhombus is the hypotenuse of one of those right triangles.
The Pythagorean Theorem tells us the length of each hypotenuse is 17.
ANSWER: RS (and each other side of the rhombus) has length 17.