I’m pretty new to WP but successfully added an RSS feed to my site by doing this:
Go to your Dashboard. Under Appearance, click Widgets. On the far right, choose the area in which you want your feed to appear and click the drop down next to that area. Find the RSS widget and drag it to that area until a little dashed box appear and place your RSS widget into that dotted box. If the widget didn’t automatically open, click the drop down next to your RSS widget. Now just enter your feed URL, name, and options. Click SAVE and you should be good to go.