Add Font in BundleConfig

I want to put a source that is in a link , tried these two ways and none works, simply my page does not load the source. Here are codes:

First form:

var linkFont = "http://fonts.googleapis.com/css?family=Open+Sans:400,300,600,700&subset=all";
                bundles.Add(new StyleBundle("~/lib/metronic/assets/global/css").Include(
                    "~/lib/metronic/assets/global/css/components.min.css",
                     "~/lib/metronic/assets/global/css/plugins.min.css"));

Second Form:

bundles.Add(new StyleBundle("~/lib/metronic/assets/global/css").Include(
                "~/lib/metronic/assets/global/plugins/font-awesome/css/font-awesome.min.css",
                "~/lib/metronic/assets/global/css/components.min.css",
                 "~/lib/metronic/assets/global/css/plugins.min.css"));

What would be my mistake?