|SUPPLIES: purchased 1/4" stabilizer such as Wright's light twill tape, pre-cut strips of fusible interfacing, OR self-made from selvedges, stable interfacing, or fabric; edge stitching foot; small ruler; one pin; extension table for SM.
I found Sandra Betzina's technique in "Power Sewing". I would follow her technique exactly for a fine fabric, but I wanted to simplify the process.
The goal is to have the edge of your stabilizing tape butt up against the seam line on the wrong side of the garment, with the rest of the tape inside the seam.
Using your ruler, line the tape up at the beginning of the projected seam line (mine was 3/8") and use one pin to hold it in place. Align the rudder of the edge stitch foot on the edge of the tape and the raw edge of the garment on the seam guide of your machine. Move the needle position to the right.
Puddle your garment on the flush surface of your sewing table so that it has no tension to pull the garment out of shape. Pull slightly on the tape as you feed it onto the garment and stitch slowly, always maintaining the raw edge on the seam guide mark and the rudder of the edge foot against the edge of the tape. The feed dogs will very slightly ease the garment to the stabilizer where needed.
The stability of your garment fabric will determine the amount of tension you would need to apply to the tape. The linen I am using for tank tops cut on the bias is lovely, but parts of the curves in the neck and armhole stretched out of shape very easily. On straight of grain sections of the neckline, I only guided the tape into place. On the bias sections, I applied more tension. The very narrow width of the tape will follow a curve. On a tight curve you could make small clips into the tape after the seam is stitched
After the binding was stitched, turned under,, and top stitched, the neck and armholes were very flat.