Including four to six key search terms in your keywords metatag won't hurt and may help your search placement, but don't load up the keywords metatag with dozens of terms.
A metatag gives a spider (search engine) specific information, such as keywords or site summaries
Metatags are hidden codes that can be embedded in the HTML source code of a web page and are searchable by search engines ITRMC has a Metatag Work Group formed to develop criteria for how and when Metatags should be used; to establish and recommend a Metatag standard for Idaho government; and to recommend an implementation process