rst-compile-toolsets

rst-compile-toolsets is a variable defined in `rst.el'.
Its value is

((html "rst2html" ".html" nil)
 (latex "rst2latex" ".tex" nil)
 (newlatex "rst2newlatex" ".tex" nil)
 (pseudoxml "rst2pseudoxml" ".xml" nil)
 (xml "rst2xml" ".xml" nil)
 (pdf "rst2pdf" ".pdf" nil)
 (s5 "rst2s5" ".html" nil))

Documentation:
Table describing the command to use for each tool-set.
An association list of the tool-set to a list of the (command to use,
extension of produced filename, options to the tool (nil or a
string)) to be used for converting the document.

You can customize this variable.