documentclass[11pt, twoside]{article}



% %%%%%%%%
% Preamble
% %%%%%%%%

usepackage[english]{babel}
usepackage[T1]{fontenc}

usepackage{%
    geometry,%
    fancyhdr,%
    lipsum%
}

usepackage[titletoc, title, header]{appendix}

geometry{%
    a4paper,%
    top=3cm,%
    bottom=3.5cm,%
    outer=2.5cm,%
    inner=3.5cm,%
    nomarginpar,%
    showframe=false%
}

fancypagestyle{general}{%
    fancyhf{}                  % Clean fields
    fancyhead[R]{itshapenouppercase{rightmark}}
    renewcommand{headrulewidth}{0.4pt}
    fancyfoot[R]{thepage}
    renewcommand{footrulewidth}{0.4pt}
}



% %%%%%%%%%%%%%%%%%%
% Begin the document
% %%%%%%%%%%%%%%%%%%

begin{document}

    pagestyle{general}

    section{Section}
    lipsum

    newpage
    begin{appendices}
        section{Foo bar}
        lipsum[1-2]
    end{appendices}

end{document}