We’ve seen it draped over the top edge of an upright bucky and attached with Velcro to the upright stand itself.
Your imagination is the limit, but please be careful not to drop it on your toes.

That being said, the original intent was to stand freely on the x-ray table, or to slide beneath the patients leg to hold it in place.
Position the sphere normally after positioning the base.

Description: 

OrthoMark OM-1001
Acrylic base, fully adjustable X-ray magnification marker designed for use with all orthopedic and veterinary surgical templating software.

For flat surfaces
Arm length: 24″
Weight: 24oz
Ball: 25.4mm/1″ Stainless