When the installation procedure is being created, the following needs to be added in the 'Parameters' section under the Embedded File tab:
>$rf
This will cause the output file to be generated so that any output that the install procedure generates will appear in this file.
NOTE:
You can also achieve the same result by passing only '$rf' as a parameter to the installation file provided that the file itself can redirect output to the variable passed in.
So for a batch file, the required lines in the batch file would be redirected to this passed-in parameter (%1)
Example: echo "this is text in the batch file" > %1
The 'Parameters' section for this job should simply contain $rf.