You might have, or can inexpensively buy, a mechanical pencil which has the feeder button on the side rather than on top, as usual. With the pencil in hand, [ptkrf] shows you the simple procedure ...

Hoover for President 1928 National Air and Space Museum Pencil Boxes, Lindbergh, King Collection National Air and Space Museum Mechanical Pencil, Army Air Forces National Air and Space Museum Pencil, ...