I got it to work!!
In case it helps someone else:
On the General tab, I left the "Configure for" setting as-is. << Not sure if that made a difference here, or not, but since it works, I'm leaving it.
In the Actions, the program/script is simply "C:\filepath\filename.rrd" << Note that the parentheses were required for me, because I had spaces in my filename.
Also in the Actions, the Start In was (without parentheses) C:\filepath <<Note that there is no ending backslash. As with the other setting, it may have worked with or without the backslash, but since it works the way it defaulted, I'm leaving it.
At least I can cross this off my list! If anyone reads this thread and has questions, feel free to post a reply and I can clarify anything that is needed.
~Lyn