In FormSketch, the menu at the bottom of the map has an option for freestyle drawing, indicated by a pen tool.
This is useful if you want to highlight areas of the map that are not necessarily angular, or to even write something in your own handwriting if using a mobile device (such as a tablet or phone). There are various options that you can use for your drawing as well:
Fill Styles:
There are four different styles you can have for 'fill', if you are drawing a closed shape or section. These are No Fill, Semi Fill, Solid Fill, and Pattern Fill.
Dash (Line) Styles:
There are also four different styles for the drawing line; Draw, Dashed, Dotted, and Solid.
Line size:
The lines can be drawn in any of four sizes; Small, Medium, Large, and Extra Large.
Colour:
There are 12 colours to select from, as well as the Opacity scale, if you would like the drawing to be solid or more transparent.
With these options, you can draw whatever you need to, whether it is highlighting particular sections or areas, wanting to add extra information, or simply preferring to draw parts of the map more freestyle.