How to attach toggle button to knitting

Hi, I need to attach this toggle to a cowl. If I use my sewing machine do I need to back it with interfacing or tear away interfacing? Or should I try to hand sew it on?
Any suggestions would be appreciated.

I think it should be hand sewn. I always sew buttons by hand.

Yes, hand stitches may be easier since I assume this is fairly small. Backing of some sort is a good idea since it would firm up the stitches.