When you perform a yank in the reply buffer set up by your reader, it
should execute the function sc-cite-original via one of the hooks
mentioned above (see section Getting Connected). Since this function is
called by a hook, it is not passed any arguments and so expects the raw
reply buffer to be very specifically formatted
(see section Hints to Reader Authors).
For the most part, sc-cite-original will do some
default things, based on your preferences, with very little direct
interaction with you. After the initial yank of the original message,
you can use various supercite commands to reformat and beautify your
reply (see section Post-yank Formatting Commands).