Problem in adding meta attribute

I want to add <meta name="fediverse:creator" content="@RezaHoss@mas.to"> to share my post in mastodon, but when I add this in the article’s content a @RezaHoss@mas.to"> is shown in the text of the article. There is no difference between when I write the article in html or markdown. What is the problem?
Is there a way to add this string to head of the page?