You need to use the github version of the knitrBootstrap package to use buttons, not panels. The CRAN version of the package has only panels. The easiest way to install a package from github is with devtools.
install.packages(devtools)
library(devtools)
install.packages('jimhester/knitrBootstrap')
library(knitrBootstrap)
, knithBootstrap github rmarkdown, rmarkdown::render.
, chunk bootstrap.panel.\
. https://github.com/jimhester/knitrBootstrap.
, CRAN, Rmarkdown CRAN, .