FYI Google (91.6% of the search engine market) does NOT use the "keywords" meta tag for SEO, and hasn't for 15+ years. Google basically ignores it all together. It was too easy to abuse and the abuse was rampant so Google just stopped using it. Bing (3.3% of the search engine market) and Yahoo (1.1% of the search engine market) followed suit shortly thereafter and now also ignore the "keywords" meta tag.
If you are looking to improve SEO the "keywords" meta tag is definitely not the way to go about it.