There is no harm done if the OP uses a standard chain on his NK Bar. . . . Even the NK chain will work on a standard bar, but maybe not as fast.
I disagree Sagetown. One might get away with it for a short time, but I think that it will lead to wear (bar and tie straps), binding, or uneven cutting issues.
Philbert
"Always use a Micro-Lite™bar with a Micro-Lite™chain. Here’s why:
To help a Micro-Lite™chain cut its narrower kerf, Micro- Lite™bars are built slightly thinner than standard bars. If Micro-Lite™chain is run on a standard bar, there may be hang-ups during the cut. And if standard chain is run on
a Micro-Lite™bar, all the performance advantages of cutting a narrower kerf will be lost."