If R is installed in a nonstandard location (or if you have multiple copies of R and you want SAS to use a particular version), you can define the R_HOME environment variable. How you do that depends on the version of Windows that you are running, but hopefully this Windows 7 example will point you in the right direction.
From Control Panel, search for "environment." Click on the link that says something like "Edit environment variables for your account". (On Windows 7, it is on the System Properties dialog, on the Advanced Tab, click Environment Variables.)
Click New in the top section for "user variables." Type R_HOME for the Variable name field and the full path of your R installation for the Variable value field.
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