German States ND Regensburg Kreuzer?

Hello,
I've had this coin on my desk for a few years and have done some extensive searching. So far I cannot positively identify it. I'm really hoping that someone will be able to help confirm that it is Regensburg, a date range and a denomination.
It appears to be silver, 17.2mm max, 1.0g
The obverse shows the crossed key arms of Regensburg and the reverse has a "K" in a shield within a cross.
There is no date.
Any help would be appreciated
Thank you

Would have been a match if there was a bit more metal between the upper arms of the K .
Other than that I only found that a K in shield is the mark of Christoph Sundtheim (1621-22) from the Cheminitz Mint .

EDIT: or it is nether the less like THIS one on eBay ... maybe an error in Krause, K for Kreuzer would make sense

This is good information, and Thank you. That is a possibility that Krause is incorrect.