R Markdownd: ! LaTeX Error: Two \documentclass or \documentstyle commands - r

Question

I am trying to knit a pdf in Rmarkdown, but I receive the same error over and over again:
! LaTeX Error: Two \documentclass or \documentstyle commands.
I already different approaches like deleting some rows, putting \begin{document} in different places or changing the order of loading packages.
This is my code:
---
title: "Feedback"
author: "Me"
date: "09 02 2021"
toc: true
toc_depth: 2
toc-title: "Verzeichnis"
fig.caption: "Tabelle"
smooth_scroll: false
header-includes:
\documentclass{article}
\PassOptionsToPackage[usenames,dvipsnames]{xcolor}
\usepackage{fancyhdr}
\usepackage[T1]{fontenc}
\usepackage[default]{sourcesanspro}
\usepackage{tikz}
mainfont: SourceSansPro
output: pdf_document
---
\begin{document}
\addtolength{\headheight}{1.0cm}
\fancypagestyle{plain}{}
\thispagestyle{fancy}
\fancyhead[L]{\includegraphics[width = 500pt]{"/Users/lisak/One Drive/OneDrive/Dokumente/Masterarbeit/Erhebung/Anschreiben/alt/banner.png"}}
\renewcommand{\headrulewidth}{0pt}
{r, echo = FALSE, message = FALSE}
.onLoad <- function(libname = find.package("kableExtra"), pkgname = "kableExtra") {
if (knitr::is_latex_output()) {
load_packages <- getOption("kableExtra.latex.load_packages", default = TRUE)
if (load_packages) {
usepackage_latex("booktabs")
usepackage_latex("longtable")
usepackage_latex("array")
usepackage_latex("multirow")
usepackage_latex("wrapfig")
usepackage_latex("float")
usepackage_latex("colortbl")
usepackage_latex("pdflscape")
usepackage_latex("tabu")
usepackage_latex("threeparttable")
usepackage_latex("threeparttablex")
usepackage_latex("ulem", "normalem")
usepackage_latex("makecell")
usepackage_latex("xcolor")
}
}
auto_format <- getOption("kableExtra.auto_format", default = TRUE)
if (auto_format) auto_set_format()
if (!is.null(rmarkdown::metadata$output) &&
rmarkdown::metadata$output %in% c(
"ioslides_presentation", "slidy_presentation",
"gitbook", "bookdown::gitbook", "radix_article", "radix::radix_article",
"distill_article", "distill::distill_article"
)) {
options(kableExtra.html.bsTable = TRUE)
}
if (!is.null(knitr::opts_knit$get("rmarkdown.pandoc.to")) &&
knitr::opts_knit$get("rmarkdown.pandoc.to") %in% c("epub3", "epub")) {
options(kableExtra.knit_print.dependency = FALSE)
}
}
stuff....
\end{document}

Answer 1

Rmarkdown will automatically insert stuff like \documentclass{article} and \begin{document} when converting the rmarkdown document into a tex document. You must not insert it a second time
\PassOptionsToPackage[usenames,dvipsnames]{xcolor} must be used before the documentclass. As rmarkdown takes away your ability to insert the document class yourself, you can't use this
rmarkdown has trouble to correctly parse the square brackets of optional arguments. As a workaround, you can hide these commands in a separate .tex file
the syntax of your r chunk is wrong. You must surround it with backticks
---
title: "Feedback"
author: "Me"
date: "09 02 2021"
toc: true
toc_depth: 2
toc-title: "Verzeichnis"
fig.caption: "Tabelle"
smooth_scroll: false
mainfont: SourceSansPro
output:
pdf_document:
keep_tex: true
includes:
in_header: preamble.tex
---
```{r, echo = FALSE, message = FALSE}
.onLoad <- function(libname = find.package("kableExtra"), pkgname = "kableExtra") {
if (knitr::is_latex_output()) {
load_packages <- getOption("kableExtra.latex.load_packages", default = TRUE)
if (load_packages) {
usepackage_latex("booktabs")
usepackage_latex("longtable")
usepackage_latex("array")
usepackage_latex("multirow")
usepackage_latex("wrapfig")
usepackage_latex("float")
usepackage_latex("colortbl")
usepackage_latex("pdflscape")
usepackage_latex("tabu")
usepackage_latex("threeparttable")
usepackage_latex("threeparttablex")
usepackage_latex("ulem", "normalem")
usepackage_latex("makecell")
usepackage_latex("xcolor")
}
}
auto_format <- getOption("kableExtra.auto_format", default = TRUE)
if (auto_format) auto_set_format()
if (!is.null(rmarkdown::metadata$output) &&
rmarkdown::metadata$output %in% c(
"ioslides_presentation", "slidy_presentation",
"gitbook", "bookdown::gitbook", "radix_article", "radix::radix_article",
"distill_article", "distill::distill_article"
)) {
options(kableExtra.html.bsTable = TRUE)
}
if (!is.null(knitr::opts_knit$get("rmarkdown.pandoc.to")) &&
knitr::opts_knit$get("rmarkdown.pandoc.to") %in% c("epub3", "epub")) {
options(kableExtra.knit_print.dependency = FALSE)
}
}
```
stuff....
and preamble.tex:
\usepackage{fancyhdr}
\usepackage[T1]{fontenc}
\usepackage[default]{sourcesanspro}
\usepackage{tikz}
\addtolength{\headheight}{1.0cm}
\fancypagestyle{plain}{}
\thispagestyle{fancy}
\fancyhead[L]{\includegraphics[width = 500pt]{example-image}}
\renewcommand{\headrulewidth}{0pt}