When selecting a drawing tool, consider the effect you want.

• Choose Tools > Comment. In the Comment toolbar, click Drawing Tools and select the drawing markup tool. 

To specify the line width, color, and other properties before you draw, select the desired tool, and press Ctrl+E to  open the properties toolbar. Set the desired options in the Properties toolbar. 

Draw in the PDF:

• To create a cloud or polygon shape, click to create the start point, move the pointer, and click to create  each segment. To finish drawing the shape, click the start point, or right-click  and choose Complete from  the menu. Double-click to end a polygon line. 
• To draw a line, arrow, or rectangle, either drag across the area where you want the markup to appear, or  click twice: once to create the start point and once to create the end point.
• To draw a square or circle, or to draw a line that’s horizontal, vertical, or at a 45° angle, press Shift while you draw. 
• To draw free-form  lines using the Pencil tool , drag where you want to begin drawing. You can release the mouse button, move the pointer to a new location, and continue drawing. To erase parts of the drawing, select the Pencil Eraser tool and drag across the areas of the drawing that you want to remove. 
• To edit or resize the markup, select it and drag one of the handles to make your adjustments. 
  
• To add a popup  note to the markup, select the Hand tool, and double-click the markup. 
• (Optional) Click the close button in the popup  note. A note icon appears to the right of the markup to indicate the presence of text in the popup  note. 

Note: To delete a drawing markup, select it and press Delete.