If you draw a circle (or any other shape) in a 'Draw' program - or from a clip-art prog, then import it as an underlay, you can simply 'colour-in' over the line with stitches to create your outline. To make it more accurate, just do a quarter of a circle (12 to 3 on a clock face) then copy and paste to make the circle. I've used this method for all sorts of outlines. Save your underlay in a separate file to use again - it's easy to change sizes.