RSS Widget not showing up

I’m having trouble getting my RSS widget to show up. The theme I’ve customized is simpla, which is really basic. I did update it so it can handle widgets, all the others seem to work fine. Is there some code I need to add somewhere to get the RSS to appear, or maybe something else I’ve forgot to do? I am a newb after all. Any help hugely appreciated.

url: thestrangeattractor.net

Thanks