You can subscribe to an RSS feed using the following link:
Type = This can be XML or RSS2.
Count = The number of items you want to be listed in the feed. This must be a number between 1 and 15.
Forumids = The ids of each forum that you want to be in the feed. Each forumid should be separated by a comma. For example "8,18" signifies "Maplestory Discussion" and "Extractions".
Here are a few RSS feeds set up for you:
Extractions and Maplestory Discussion
Extractions, Maplestory Discussion, and Training Center
The RSS feed always assumes it's a guest to whatever forum it's visiting. This means that you cannot use an RSS feed on forums that are members only (social section).