In the Tools toolbar, select the Pencil tool or press Alt + /.
The Pencil tool properties appear in the Tool Properties view.
Use the Size slider to set the size of your pencil line.
Use the Smoothing slider to set the amount of smoothing Harmony should perform on your pencil lines. A higher setting will prevent your line from being shaky, but is liable to reduce your drawing precision and to round sharp corners into curves.
In the Camera or Drawing view, start drawing to test your pencil settings.