Newbie needs help

What's the easiest way to place a keyway onto a round shaft? I tried dragging one of the keyways from the Design Library but it wants to be placed on a planar face. I thought using a reference plane might be the answer but I can't quite figure out how to place it tangent to the top quadrant of the shaft and parallel to the default top plane.
Mike S.

I sent you a sample.
WT
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Mike,
When creating the reference plane, you can specify it to be "on surface". It will be perpendicular to the input place and by viewing "other solutions" the result can be shifted to the opposite outside tangent position on your cylinder. (Do not use the "normal Plane" option.)
Per O. Hoel

Thanks for the help guys!
Mike S
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