Following the instructions here will enable one to choose an R kernel. Note that there is a ton of output from R when running
install.packages("deftools") because it’s building it from source.
If one is not doing a lot of R development then create an environment that can be switched into using
source activate <env-name> when R notebooks are needed. I do this because R is a ton of code that could crap up your root Python install.
(This is an alternative description of how to set up R in Jupyter and includes steps that work for Jupyter Notebooks and Jupyterlab.)