Awhile ago (talking 4 months ago) I cancelled an appointment after I had provided my rs2k verification info. Can a Provider add a negative report against my record because I cancelled the visit even though I did it in a respectable way (explaining the circumstances) and with plenty of notice?

I do not know what RS2K allows providers to say regarding cancellations.  It happens all the time, both on their part as well as ours, after all shit happens on both sides of the fence.  If you gave her enough notice, she prob will not do anything detrimental to you.  The best way to make amends is to try to reschedule your date with her.  That way, she still knows you are sincere in your desire to spend time with her.

Schedule changes, flight changes etc happen all the time. You shouldn't have to worry about a negative report.  If a no call no show some will document but not for a cancel with notice.  Life happens!  If you are still a member of R2SK you could certainly ask them if any negative reports are attached to your profile.