Font "Century Gothic" is not displayed on Windows Computer

I’m sorry to ask you but I have a problem on a site with the ‘Century Gothic’ font. I have already read some forum articles and tried, but it did not help. On my Mac everything is perfect but on a windows PC it shows an Arial Font, no matter what browser I use (IE, FF, Chrome). Do you have an idea waht’s the solution?

Kind regards and thanks for your help
René

The website ist : cocosam.ch
I already copied these lines into the file ‘functions.php and selected the font in the General Styling options:

add_filter( ‘avf_google_heading_font’, ‘avia_add_heading_font’);
function avia_add_heading_font($fonts)
{
$fonts[‘Century Gothic’] = ‘Century Gothic’;
return $fonts;
}

add_filter( ‘avf_google_content_font’, ‘avia_add_content_font’);
function avia_add_content_font($fonts)
{
$fonts[‘Century Gothic’] = ‘Century Gothic’;
return $fonts;
}