1. Open ps, hold down Ctrl O on the keyboard at the same time, and insert the picture that needs to be added with a straight line symbol according to the path selection
2. Find it in the toolbar on the left side of ps If any of these options shown on the picture is a straight line tool, just click on it
3. Click and drag the left mouse button on the corresponding position of the picture to draw a straight line
4. Pay attention to the direction and length of the straight line when drawing, as shown in the figure below: