PROC.EXE is part of the Oracle 11g 32bit Client software.
The default location on Windows, if not overridden by the installer, is something like the following.
C:\app\<YourUSERID>\product\11.2.0\client_1\BIN
In the Build Tool / Profile Manager for DBMS Oracle, there are tokens that need to be set correctly. Some tokens rely on environment variable ORACLE_HOME to be set correctly.