\chapter*{R\'esum\'e}
\chaptermark{R\'esum\'e}
\markboth{R\'ESUM\'E}{R\'ESUM\'E}
\addcontentsline{toc}{chapter}{R\'esum\'e}

\stoptoc
\renewcommand\thesection{\arabic{section}}
\setcounter{section}{0}
\renewcommand*{\theHsection}{Res.\the\value{section}}

...

\renewcommand*{\theHsection}{\theHchapter.\the\value{section}}
\renewcommand\thesection{\thechapter.\arabic{section}}
\resumetoc