Actually, I just tried at and it works directly with the editor too.
Code:
<!DOCTYPE html>
<html>
<head>
<title>metadata title</title>
<meta name="Author" content="NAME" />
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
<meta name="tags" content="categort1, category2" />
</head>
<body>
</body>
</html>