Well, let me be the first to welcome you to the forum.
As for your question, a Stillwater is made to be worn on your natural waist, about an inch or two above the navel, down to the topp or mid knee cap. The kilt should be snug enough to where the straps and buckles will hold it in place. If not, then buy a kilt belt, that should help. Anyway, enjoy your kilting!!!