Uploaded webfont not rendering correctly?

I have uploaded a couple of webfonts to use on my site and they are rendering on some browsers slightly bolder than they should be. Is there a way to insert the code below to fix this issue?

-webkit-font-smoothing: antialiased; /* This needs to be set or some font faced fonts look bold on Mac in Chrome/Webkit based browsers. */ 
-moz-osx-font-smoothing: grayscale; /* Fixes font bold issue in Firefox version 25+ on Mac */