Question
How do I verify that Rstudio is using Rtools installed in my user profile?
Answer
1. Using RStudio > Console pane, enter 'Sys.which("make.exe") ' at the prompt.
The resulting path string shows the location of your Rtools installation. Confirm it resides in your user profile and is writable so it can be used without administrative privileges.
Example for Rtools 4.5 under user TrumanT: "C:\\Users\\trumant\\rtools45\\usr\\bin\\make.exe"

2. With the devtools package installed, at the RStudio > Console prompt enter 'devtools::find_rtools()'. This should return TRUE as shown below, verifying Rstudio is using your Rtools installation.
