\documentclass[12pt]{scrreprt}
\usepackage{geometry}
\geometry{left=3.5cm,right=3.5cm,top=3cm, bottom=3cm}
\usepackage[utf8]{inputenc} 
\usepackage{amsmath,amssymb,amsthm}
\usepackage{setspace} 
\usepackage{lmodern}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usepackage{placeins}
\usepackage{subcaption}
\usepackage{booktabs}
\usepackage{longtable}  
\usepackage{caption}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{float}

\usepackage{tikz}
\definecolor{smedarkblue}{RGB}{0, 36, 76}
\definecolor{smelightblue}{RGB}{0, 72, 153}
\definecolor{smeorange}{RGB}{255, 155, 0}

\setlength{\parindent}{0mm} 
\setlength{\parskip}{5mm}

\begin{document}

\input{include/content.tex}
\pagestyle{plain}
\pagenumbering{roman}
\setcounter{tocdepth}{1}
\pagenumbering{arabic}

\appendix
\addcontentsline{toc}{chapter}{Appendix}
\end{document} 