Depending on your browser and platform you need to specify the font in different formats.
See this example:
@font-face {
font-family: "LeagueGothic";
src: url('../fonts/league_gothic-webfont.eot');
src: url('../fonts/league_gothic-webfont.eot?#iefix') format('eot'),
url('../fonts/league_gothic-webfont.ttf') format('truetype'),
url('../fonts/league_gothic-webfont.woff') format('woff'),
url('../fonts/league_gothic-webfont.eot#iefix') format('embedded-opentype'),
url('../fonts/league_gothic-webfont.svg') format('svg');
font-weight: "normal";
font-style: "normal";
}
If you just have the font in .ttf format and need the others, you can use the FontSquirrel’s WebFont Generator to create your own @font-face kit.