Pencil
To mark specific regions on the image by drawing free-form lines:
Click Annotate on the menu bar.
Click Pencil 
.
Draw free-form lines.
Note
The pencil annotation line thickness can be chosen.
Right-click to finish.
The line is shown in the viewer and added to the Annotation tab 
on the SmartPanel. Click 
to change the color or delete the lines. To move the pencil annotation, click and drag the annotation on the viewer.