I usually have the bottom edge of my kilt pin at about 6" up from the bottom edge of the kilt, and about 2" to 3" in from the apron edge. As Rivekilt said I tend to place my kilt pin, especially sword shaped, or horse-blanket pin styles in a manner that to my eye looks good on the section of the sett where they lay. To me wearing it too high doesn't seem to feel right, but I know Robert does this with great success.