To Draw a Circular Edge on a Face of a Solid

Select the Draw on Solid tool.
Select the Draw Circle icon.
Enter a data point on the required face.
The face becomes selected as the draw on face.
Enter a second data point to define the center of the circle.
Enter a third data point to define a point on the circle.
The circle, or part of the circle that will fit on the face, is drawn on the face of the solid.

Left: Enter two data points to define the circle.Right: The completed circular edge on the face of the solid.