The simplest way to get a note into PDF format is to use OS X's built-in Print to PDF function. Just select the note you want, open the print dialog, click the PDF button in the lower left corner, and select Save as PDF.
If you want to script/automate it, you can either do some GUI scripting to Automate the PDF printing process (which is a bit clunky, but there are many examples of how to do this around), or you can get the note text as HTML via AppleScript and convert it to RTF. Note that in either case, you just get plain text, the legal paper style of Notes is part of the GUI, not the note format.
If you want to get the text of a note in RTF, you can use this AppleScript:
tell application "Notes"
set theNote to first note
set theFile to ((path to desktop as text) & "output.html")
my write_to_file(body of theNote, theFile, false)
do shell script "textutil -convert rtf " & (POSIX path of theFile)
on write_to_file(this_data, target_file, append_data) -- (string, file path as string, boolean)
set the target_file to the target_file as text
set the open_target_file to ¬
open for access file target_file with write permission
if append_data is false then ¬
set eof of the open_target_file to 0
write this_data to the open_target_file starting at eof
close access the open_target_file
close access file target_file
This prints the first note in the list, if you want a specific one, or all of them, you can modify it to loop over the notes.
Hopefully that's a helpful starting point. I haven't had the time to look at how to export Reminders, perhaps someone else can chime in with that.