Some leagues require that a match config e.g. match.cfg be executed on the fly so they know the config is correct. ClanForge is a little different in the way it handles these than traditional ftp based hosting.
To add a the custom config file you need to go to ClanForge -> Profiles -> Config. Once there click Browse and select the config file from your machine, next click Add and the file will be uploaded into your profile. Complete this by clicking save.
You now have your custom config file e.g. match.cfg present on your server. To exec it you need to use the following:
rcon exec <serverid>/match.cfg
To find out what your <serverid> is look in ClanForge -> Servers -> details
For more information on using ClanForge please see: