Singer Overcasting Edge Presser Foot
The Overcasting Edge Foot will give you a similar finish to that of an Over locker. It takes the stitches over the edge of the fabric with the small bar in the center of the foot which wraps the thread around the edge of the fabric as you sew.
Your machine may have some overcasting stitches already. Consult your machine manual for which stitches are for overcasting. Or alternatively you can use a zig zag stitch. When using a Zig Zag stitch make sure that the needle does not hit the bar in the center.