Making a port that installs only an RC script provided in FILESDIR

[Mel Pilgrim]

I have a port that has exactly one file: an RC script provided in the 
FILESDIR of the skeleton itself.  I can't use metaport because I do have 
to install a file.

I've had no luck finding anything that explains how to do this, and am 
meeting no end of errors when I test the port.

How do I create this kind of port?