I read about these several questions, how to use a font size other than 10, 11 oder 12 (see e.g. this one) using KomaScript, but somehow, that won't work for me. I use XeLaTeX to compile my document (in order to change the font also, but the problem already occurs without that).
Then using the MWE
\documentclass[fontsize=13,DIV=12]{scrbook}
\usepackage[no-math]{fontspec}
\usepackage{xunicode,xltxtra}
\begin{document}
Dieser Text sollte in Schrift 13pt sein, ist aber 12pt
\end{document}
The warning then is
LaTeX Font Warning: Font shape `OT1/cmr/m/n' in size <13> not available
(Font) size <12> substituted on input line 1366.
Which i suspect is due to OT1 but how do I tell XeLaTeX to use T1 (also because it's a german text, as the MWE might already suggest)?
fontsizeoption actually does – cgnieder Aug 22 '13 at 09:2513pt\normalsizeand not still 12pt, because the 13pt are available with the font i use (or even XeLaTeX uses normally). – Ronny Aug 22 '13 at 09:39