@font-face {
font-family: "jf-flat";
src: url("JF-Flat-regular.ttf");
src: url("JF Flat Regular.otf") format("opentype");
}

 
/*
After update:

@font-face {
font-family: "CustomFont";
src: url("https://yoursite.com/css/fonts/CustomFont.eot");
src: url("https://yoursite.com/css/fonts/CustomFont.woff") format("woff"),
url("https://yoursite.com/css/fonts/CustomFont.otf") format("opentype"),
url("https://yoursite.com/css/fonts/CustomFont.svg#filename") format("svg");
}*/