I assume you’re not actually trying to “put a rss link” into your sidebar, but to actually parse the RSS feed, like the RSS widget does.
Take a look in widgets.php for function widget_rss()
or something like that. Copy that code into your sidebar with whatever modifications are necessary (e.g. replacing the calls to get_option with defined variables).
These php files are absolute greek to me, for the most part. I’d like to do the same thing, but I can’t figure out what part of the code to add to my sidebar. Any help would be greatly appreciated.
There’s an example in the codex:
Function_Reference/fetch_rss