This brief tutorial explains how to add external images to an R Markdown notebook. While there are multiple ways to accomplish this, and very specific libraries that extend the core capabilities of Knitr, the scope of this tutorial is limited to the use of include_graphics() function.
Most of the work to manipulate image output to the HTML file is done in the code block header
Note: These settings only apply to HTML output. External images output to Word docs must me manually manipulated in Word.
knitr::include_graphics('C:/Users/drhea/Desktop/fb_pic.jpg')