I always use google if I can't spell a word, spell checker does not do it for me. The one on this site uses US spellings as well.
Thank you voters.
I keep an extra tab open and do google searches. It is smart enough that if you had simply typed the search "rithm adn blues" It would have corrected both mistakes and you would have had the correct spelling in 2 seconds.
You have to keep in mind that you are probably using a free spell checker. It is worth 'free'. Like most tools, they help get the job done but are not an end all solution.
I use this online dictionary. If I misspell a word, it takes me to a page with the corrected spelling ans suggested sentences to see if that is the actual word you are looking for.
http://www.yourdictionary.com/ tried it with rythm
and it took me to this page.
Check it out. I think you will find it fast and easy.
Try having a computer where the default language isn't even english. Just that line says that I have a typo for the words: Try, having, where, language, isn't, and english.
I'm English and my spellchecker online is American, so it's always correcting me.