I would recommend you to follow https://github.com/RevolutionAnalytics/rhadoop/wiki/Installing-RHadoop-on-RHEL to install RHadoop . 
One more important thing is to go through the description file and install all the dependencies mentioned over there. 
Installing RHadoop 
Package - Where to Install 
plyrmr - On every node in the cluster 
ravro - Only on the node that runs the R client 
rhbase - Only on the node that runs the R client 
rhdfs - Only on the node that runs the R client 
rmr2 - On every node in the cluster 
Installing rmr2 
1. Download rmr2 from here. 
2. Download the R packages dependencies for rmr2. Check the DESCRIPTION file for the most up-to-date list of dependencies. 
3. Install rmr2 and its dependent R packages. 
4. Update the environment variables needed by rmr2. 
This is common step for installing all the r package.