Open D-Fend Reloaded
Click the profile you want to use
Open the profile settings
Go to the Program or Main tab
Set the executable to your .bat file
If needed, change the start directory to the folder containing the .bat file
Add any required command-line parameters
Save the profile
Run the profile from D-Fend Reloaded
If the .bat file does not launch correctly, create a shortcut or wrapper EXE and use that instead