Most of us know what the RSS icon looks like. It is that ubiquitous symbol that appears next to an actual RSS feed, with the little dot at the bottom left hand corner and the two lines, one longer and more arced than the other, hanging over that dot. The RSS icon indicates to people that a feed exists on any particular website in operation, so it obviously serves a great purpose. What we do with these feeds and with the RSS feed icons that accompany them, however, is far more important than the RSS icon itself.
Of course the content matters far more than the symbol or the RSS icon that appears, but if your site will be developing or adding a feed in the near future you will need an RSS icon to accompany it. It helps users who visit your site to know that your content comes from a feed, and it indicates to them that you are very interested in giving them information that is outside your realm to further their own knowledge of specific subjects.
In order for people to know about your feed, an RSS feed icon will be necessary. Without it, your feed may look out of place or it might confuse your website visitors. The last thing you want to do with your site is confuse people, with your design, with your content or with anything else. User friendliness is the No. 1 reason users stick to websites today, so ensuring that the RSS icon appears prominently is of vital importance for you.
Normally, you could easily find an RSS icon on the same site as an actual RSS feeds list where you plan to pull your information. However, outside websites will allow you to save the typical icon for RSS feeds so that people notice that you have a feed. These sites, both the ones with the RSS feed list and the one outside of that realm (perhaps a site specific to saving images and icons), should enable you to complete a download at no cost.
If you wind up on a website that will charge you for an RSS icon, move on. There are lots of other places where icons can be downloaded and saved. Once you find one that matches with your color scheme or that is the most appropriate size for your feed, simply place it next to the feed and link it to that feed so users can just click once to use it.