You do not have to include comment delimiters in the file header text. ReSharper will automatically insert proper delimiters for the specific language when the header text is applied.
File header text
This field contains plain text with optional variables that will be added in the beginning of files and wrapped in comment delimiters.
The variables displayed to the right of file header text have rather self-explanatory names and you can use it in the header text to keep it up to date without manual changes. Click on a variable to insert it in the header at the current cursor position.
Embrace File Header into Region with Name
Name for a region that the file header will be wrapped up with. If this field is left empty, file header is not surrounded by region.