@Riccardo: The best option to change the font only for your site title then go to “Appearance => Theme Options => Font Family Options” and then change the site title fonts. If you don’t see your font in the list and it’s Google fonts then we can add in future version update for your use. But if this font in not available as Google Font then you need to build child theme and do the font embed.
For Font Face Embedding, I recommend you to generate font from http://www.fontsquirrel.com/tools/webfont-generator and download your font files. You can add those font files in your child theme. For example you added your font files are WebFont.eot, WebFont.woff, WebFont.ttf and WebFont.svg in your child theme directory. Then you need to add the css in your child theme style.css as following:
@font-face {
font-family: 'MyWebFont';
src: url('WebFont.eot');
src: url('WebFont.eot?iefix') format('eot'),
url('WebFont.woff') format('woff'),
url('WebFont.ttf') format('truetype'),
url('WebFont.svg#webfont') format('svg');
}
#site-title {
font-family: 'MyWebFont', Arial, sans-serif;
}