|I have been using this knit fabrics to finish off my facings. Usually I just serge them but this looks better, adds no bulk, and is easy to do. I hate using woven bias tape because I hate buying something that I can make. But, I hate making it and it never folds perfectly for me. Here are the steps for adding it to the facings of your pants or skirts.
First, if there are several pieces of facing, you'll need to sew those together first. You should have one continuous strip that you are ready to sew to the garment.
When I am ready to apply a binding, I look through my pile of scraps. You'll need a piece of thin knit (like a polyester jersey) that is at least an inch wide the entire length. I trim one side so it is straight and leave the other side ragged. As long as it is at least one inch along the length of the strip, it will work fine. Make sure the stretch is going the long way on your strip of knit. Make the knit piece a bit (1/2" - 3/4") shorter than your facing piece.
Next, place the knit and facing together right sides together. Use a 1/4" seam to attach the knit to the facing. You'll need to stretch the knit a little to make it fit the length of the facing. You can use whatever size seam allowance you want to connect the two pieces. A larger seam will require a wider strip of knit binding. I would just make sure to test it out before you start stitching it down.
Now, flip the knit binding to the back side of the facing.
Now sew on the right side of the facing just off the knit binding. You should aim for a "stitch in the ditch" kind of placement. Make sure you catch the ragged edge of the knit on the back side of the facing. If you made your knit strip too narrow, you can trim off some of the facing seam allowance so you don't have to cover as much of the facing with your knit binding. You can see in my picture how my stitches are close to but not on the knit binding.
Look at the wrong side of the facing and trim the knit close to the seam allowance.
All done. Now when you attach your facing, the bottom will be finished.