Usually the RSS link should appear at the bottom of the page for your bookmarks with a particular tag. Here's the structure of the URL, using my links tagged "collaboration" as an example.
If you want to add a feed of your delicious bookmarks for a certain tag(s), here is how:
1. Navigate to your iGoogle page, and click on Add Stuff button
2. type "delicious" into search for gadgets search tool
3. I chose "Del.icio.us bookmarks" from search results.
4. return to igoogle page where you will see the delicious feed
5. click on "edit settings" from the delicious feed
6. configure by setting your username, Display "all links", and typing your tag(s)
7. save settings
I hope that is what you are looking for. I realize this advice is coming at you very late...