Alignment for curve

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I should know this but my brain is a bit foggy.  I have a face groove detail on a cylindrical part.  View shown below is from the -Y direction.  The Z depth of this groove has been problematic for reasons I don't know.  The drawing is calling for profile of 2 radii within the curve.  If I take a point in the -Z direction at the bottom, where the 2 radii are tangent, I believe that will give the curve enough information to locate it for measuring. Will a geometry best fit alignment from the point do the job? 

 

Edited 10 hours ago