No luck on finding a website for KMG.
The 'compatibility lookup' on the original ebay listing shows the KMG Pad 18 is designed fit a 1985 K100RS. An Amazon listing for the KMG Pad 18 indicates it is a compatible replacement for the EBC FA18. And a Summit Racing lookup indicates the EBC FA18 is designed for the 1985 K100RS. So the daisy chain of logic indicates that the KMG Pad 18 should fit the K100RS. But, knowing the typical quality and attention to detail found in Chinese-made parts, the holes were probably stamped too large. I dunno whether I should bother using these or not.
The reddish-orange stuff on the back of the pad had a rubbery consistency like dried silicone caulk. I guess I just wasn't expecting that.