Since at some point I had trouble with a conflict between knitr and the latex package textpos, I used the lesser Sweave in Another Experiment with R and Sweave. I ran the Sweave2knitr command and discovered that textpos and knitr play well together now. Here is the result using knitr (go to https://www.box.com/s/4nftk6qpa0cugapmncsn if the embed does not show below):