Are you reading the labels on the converter or the caps? I think the R in "KR" might stand for Ricoh, who used the K mount for their cameras and lenses. Everything was fine until Ricoh came up with a variation for the Ricoh Program cameras and lenses. Later Pentax came op with screwdrive AF. These Ricoh lenses had a pin which might drop into the screwdrive hole and semipermanently attach a $5 teleconverter to your shiny new DSLR. It makes you feel pretty bad until you get the thing back off. So although I have never seen a TC with the pin, I feel like I should mention it. If the TC's camera mount looks like this:
you're fine. It will work like an M lens - green button, stop-down metering, that sort of thing. See the sticky at the top of the thread list for details. If there are electrical contacts, especially a pin like shown on the right side of this photo:
then use caution. It gets tricky because the contacts closer to the lens locking pin slot, at the top of the photos, are useful KA-mount contacts. A TC might have 7 contacts here, grouped together. Those make the TC pretty useful. A contact by itself, further to the right and possibly larger, is a potential problem. A lot of these contacts go on and off without getting stuck. I've used the lens pictured here for years without problems. But as I say, you don't feel great when you've got a cheap useless lens stuck on your new camera.
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