\documentclass[12pt,a4paper,paper=a4,oneside,titlepage,pdftex]{scrreprt} 
%encoding specific packages
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[english,ngerman]{babel}
%\usepackage[a4paper,left=40mm,right=20mm,top=30mm,bottom=30mm]{geometry} %wers mag???
%load additional packages ...

\begin{document}

%frontmatter
\pagenumbering{roman}
\include{titlepage}
%etc. ...
\end{document}