Not familiar with those. They may have been offered by one of the Authorized Randall Dealers like the late Rick Bowles, who passed away a few days ago.
The only buckles most of us have or had were the leather buckles made by Greg Gutcher of Sullivan's Holster Shop, who is the current supplier of Randall Sheaths.
They have "Randall Knives" stamped on the front, covering most of the leather face, that could be attached to a leather belt that allowed interchangeable buckles.
Some buckles had Greg's signature in ink on the back side of the leather. They were made in limited numbers, I think maybe less than 100 for each year Greg offered them.
_________________________
Buck Buchanan, RKCC #CM-16, RKS #1003
NRA LIFE
NMLRA LIFE
Authorized Randall Dealer
buck100_10x@icloud.com