Good question.
I did not want to use the USB cable to download feeds. Here is what I am test-driving for wireless and my comments to date as a US user.
Calibre -- popular as it has own subject area on this forum; multiple uses, not just RSS sender; many popular RSS feeds are available but I cannot create "recipes" on my own; use 5-way switch to navigate between articles in a feed; need to open calibre on your computer to send feeds; free and no charge from amazon. I don't know why there is no amazon charge for books or RSS feeds sent from calibre.
https://www.mobileread.com/forums/showthread.php?t=32543
Feedbooks -- was mentioned already but not the service that allows you to download a feed once and then update it from your kindle. no need to open a program on your computer or get charged by amazon.
https://www.mobileread.com/forums/showthread.php?t=24949
cannot use 5-way switch to navigate, use TOC or next page instead.
Kindlefeeder -- most user friendly for adding feeds to your list to send, IMHO. you need to log-in to send feeds but this can be done from any computer or I assume,the kindle. free to use but 15 cent charge from amazon. For a $20 annual fee, the web site says you can avoid the amazon charge and the need to log-in ... RSS feeds will be sent automatically as the user schedules.
http://kindlefeeder.com/
Another useful service is Instapaper, which allows you to save articles from the web and send them to your kindle. Too cumbersome for reading RSS feeds on a daily basis but good for longer web articles you want to read later. I have it set up to send me on Friday the articles I saved that week. The amazon 15 cent fee applies.
http://www.instapaper.com/
hope this helps