If it's that bad you can always use a brick to rest the foot against. Wrap it in some fabric and put it on the floor behind the foot.
If that doesn't stop the foot from "walking" then you are not pressing the foot, you are pushing it (which I do all the time). And if you can't stop you might just have to nail the foot in place lol
I just go hunt for the foot when it disappears under my cabinet.