localization - r-markdown: German quotation marks for pdf_documents

Question

I coudln't find out how to use the "lang: de" option (link) properly. That is, while tables are correctly named "Tabelle", the following settings:

---
title: "German quotation marks"
author: "will"
date: "24 J?nner 2018"
output: pdf_document
---

"Das ist sehr sch?n", sagte sie. 

Produce this output:

whereas the following is needed:

Answer 1

Following Tobi we can define language and use latex package csquotes.

---
title: "German quotation marks"
author: "will"
date: "24 J?nner 2018"
output: pdf_document
lang: de
header-includes:
  - usepackage{csquotes}
---

"Das ist sehr sch?n", sagte sie. 

Yields: