Slide the compass along the floor over the board's length, keeping the points aligned vertically. With a circular saw set for a 2- to 5-degree bevel, cut alongside the scribe line so the face of the cut will be on the side toward the wall. Trim the beveled edge down to the line with a block plane. When the scribed baseboard is put back on the wall, its top edge should line up with the chalk line snapped in Step 3.