How to insert lines in a PDF file
1. Use WPS Office to open the PDF file.
2. Click the Insert tab → the Shapes drop-down button → the Line option, then we can enter into the “Drawing tool” editing state.
3. Hold down the left mouse button to draw lines.
4. Click the line to get into the Shape Appearance tab. In the editing state, we can select the Fill Color, Border Color, Style, Line Width, Start and End of the arrow.
5. Finally, click the Exit button to exit the current editing state.