The optimal placement depends on what the RSS feed contains. For example, some sites provide multiple RSS feeds from the same core data set.
I worked on a system that collected reporting for an organization from around the world. These reports were organized based on origin, topic, and date (think geo-location and tags). The organization's analysts and the analysts from cooperating organizations only cared about slices of information. Once the user narrowed their scope of what they wanted, they could get a dedicated RSS feed for that scope.
In this case, we had a link for the custom RSS feed in the right panel above the tag cloud for the feed. The list of items was in the left panel.
This particular system also supported comments, and for particular hot topics it was useful for the analysts to have an RSS feed for that one article. The only had to look in the same location for the RSS feed when they were looking at an article.
Does this mean that everyone should have a 2:1 split and have RSS links at the top of the right panel? Hardly. It takes time to understand your audience. It made the most sense for this project. It seems to make a lot of sense for blogs. However, you may want to emphasize the RSS feed more by having the link at the top and bottom of the lists. Or you may reverse the split we had. You just have to fit it into your design and remain consistent with it's placement.