R markdown format title - pdf output

For a smaller title section, the following may be helpful. It builds on eipi10's answer but with two modifications:

1. the vspace{} commands include negative values to shrink white space
2. the fontsize code uses the more cumbersome begin{} and end{} syntax because, with simpler code like \normalsize{}, I found extraneous braces appeared around the title, name, etc.

---
title: \vspace{-0.75cm} \begin{normalsize} My Title \end{normalsize} \vspace{-0.5cm}
author: \begin{normalsize} My Name \end{normalsize}
date: \begin{normalsize} 5/16/2017 \end{normalsize}
output: pdf_document
---