Add one in manually and export it via the rum console.
Be careful - the field delimiters are semi-colons ";" and the IP ranges are delimited with a comma ",".
After exporting I open the file in a text editor. Substitute the commas for hash "#" and then substitute the semi-colons for commas. The format will go from:
Simply open the file in excel and the columns will be imported properly.
Add sites to the list. Include the old sites as the import process will only bring it the sites explicitly in the import file. Any absent sites will be removed from DCRUM.
Save the file as a csv - reverse the substitution and import the list in the RUM Console.