No, you will not need to restart Apache.
You will need to "hard refresh" your web page to see the changes. Simply browse your site and go to the page that should be affected. Then hit Ctrl + F5 to refresh everything. (Some computers require the F Lock to be on before you can use F5.) Now you should see your new .htaccess code take effect.
Alternatively, you can clear your browser's cache, close the browser, relaunch the browser, and try your web page again.
Safari users : Safari will require you to use the cmd + R hotkey for Safari 3 and below. Safari 4 and above will require that you hold shift and click the refresh icon next to your address bar.