\usemodule[rst]

\defineRSTinclusion [first][inc-first.rst]
\defineRSTinclusion[second][inc-second.rst]
\defineRSTinclusion [third][inc-third.rst]

\startRSTproject
\RSTinclusion [first]
\RSTinclusion[second]
\RSTinclusion [third]
\stopRSTproject