%%
%% The LaTeX Companion, 3ed
%%
%% Example 3-1-10 on page I-134 in "Specifying tracking, extra kerning, and adjusted spacing".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.0pt}

%StartShownPreambleCommands
\usepackage[english,french]{babel}
\usepackage[kerning]{microtype}
% \SetExtraKerning ... as above
\DeclareMicrotypeBabelHook{french}{kerning=french}
%StopShownPreambleCommands

\begin{document}
FRENCH: Je ne parle pas français! \par
\selectlanguage{english} ENGLISH: I speak English!
\end{document}