Yeah, that's sounds right, when R Studio starts up you may need to choose between 32-bit and 64-bit, based on what version of Excel you are running.
https://sites.google.com/site/rforfishandwildlifegrads/home/week_2/default32bit
Now, to run an R script from Excel, do something like this.
Sub RunRscript1()
Dim shell As Object
Set shell = VBA.CreateObject("WScript.Shell")
Dim waitTillComplete As Boolean: waitTillComplete = True
Dim style As Integer: style = 1
Dim errorCode As Integer
Dim path As String
' path to R executable: C:\Users\rshuell001\Documents\R\R-3.2.5\bin\x64\R.exe
' path to R script: C:\Users\rshuell001\Documents\R\Download.r
' see more setup details here
' http://shashiasrblog.blogspot.com/2013/10/vba-front-end-for-r.html
path = "C:\Users\rshuell001\Documents\R\R-3.2.5\bin\x64\R.exe CMD BATCH --vanilla --slave C:\Users\rshuell001\Documents\R\Download.r"
'path = """C:\Users\rshuell001\Documents\R\R-3.2.5\bin\i386"" C:\Users\rshuell001\Documents\R\Download.R"
errorCode = shell.Run(path, style, waitTillComplete)
End Sub
That scenario works fine for me. Just modify it slightly to suit your specific needs.