Alternative to Rubber Feet
I use self-stick felt pads from Home Deport, Lowe's, or hardware stores. These pads are traditionally used under table-top lamps, vases, and the like. They come in beige and brown and in different diameters and are ~1/4" thick. Perfect for arranging the height of a keyboard. My keyboards don't move with the felt pads in place; yet the keyboards slide with ease when I move them under the elongated shelf that holds my monitor. and other desktop items. Also, using felt pads gives one latitude with respect to the increments one can raise both the F-key and even space-bar edges of a keyboard, some I know raise their entire KB. Also, felt pads are available in ~1/10" in different diameters.
On my recently 'reacquired' Corsair K65, my preference is one felt pad under each space-bar corner; and three columns of three felt-pads under the F-key edge.