R markdown decrease margin

---
title: "Habits"
author: John Doe
date: March 22, 2005
geometry: margin=2cm
output: pdf_document
---

---
title: "Habits"
author: John Doe
date: March 22, 2005
geometry: "left=3cm,right=3cm,top=2cm,bottom=2cm"
output: pdf_document
---