This is on my style.css sheet:

@font-face {
font-family: ‘DINPro’;
src: url(fonts/DINPro-Black.otf?’) format(‘otf’), url(‘fonts/DINPro-Bold.otf’) format(‘otf’), url(‘fonts/DINPro-Light.otf’) format(‘otf’), url(‘fonts/DINPro-Medium.otf?’) format(‘otf’), url(‘fonts/DINPro-Regular.otf’) format(‘otf’);
}

and this is in the custom css box:
{font-family: DinPro !important; font-weight: light;}

There is a font folder in wp-content/themes/flexform/css while we included a ”fonts” folder in wp-content/themes/flexform/
Maybe the “fonts” folder is not located in the right place?