To finish constructing a copy of segment \( \overline{PQ} \) using point \( R \) and the arc, the final step involves connecting point \( R \) to the endpoints of the original segment \( PQ \).
The correct action would be:
Using a straightedge, draw a line from point \( R \) to point \( Q \).
This is because \( R \) is already aligned with the midpoint of the original segment \( PQ \), and by drawing a line to \( Q \), you’ll effectively complete the construction of the segment \( \overline{PQ} \).