Jim Fitzsimmons wrote in a message to All:

 JF> Hello All,
 JF>  I need to use the RC program that compiler a source.rc file that
 JF> is used with the main source code for the main executable. 
 JF>  Here's the problem I do not have the OS/2 software developers
 JF> toolkit but I have the RC compiler as it was included with Os/2
 JF> Warp. When I attempt to compile the source.rc file I receive the
 JF> error from RC that it cannot include the OS2.H file. My path for
 JF> include files is correct in Config.sys. Is this an error because I
 JF> don't have the ToolKit for OS/2 package? Ie: Does RC call another
 JF> program that I am missing?
 JF>  I "can" compile the source.c with EMX/Gcc, But cannot us the
 JF> source.rc file  which has the menus defined in it.
 JF>  Thanks for any suggestions or pointers...

Put this in your config.sys file:
set INCLUDE=X:\EMX\INCLUDE;X:\EMX\INCLUDE\CPP

X: being the Drive where EMX is installed.
For some reason, this was left out of the documentation.
Do not confuse this with the C_INCLUDE_PATH and the CPP_INCLUDE_PATH

 - Daniel Morgan 
--- timEd/2 1.10