Hi Geneva -
I now have a teflon foot, which makes things easier. But I've also successfully used my walking foot before I got the teflon foot. You definitely have to keep the vinyl lifted off of the machine bed because it really sticks to the metal there. You can put tissue paper between the vinyl and the machine bed and that helps, but it can be finicky controlling all of that while sewing. I just kept my left hand underneath the vinyl while I was sewing to keep it off of the bed. It also worked better for me to keep the vinyl on the top while sewing so that it was only touching the foot rather than the feed dogs. I had assumed with vinyl that I would have to use a larger stitch length, but I've never had a problem with short stitch lengths causing the vinyl to tear apart, so I used my usual shorter length when sewing this.
The next time I sew a bag with vinyl pockets, I'll try to remember to take more pictures and write a blog post about it.
Thanks!