I am assuming you might have installed Belgv facebook login extension. YOu are not able to see the facebook login button because you haven't copied the template file to your theme rwd.

1. Goto design->frontend->default->Layout and design->frontend->default->template

2. copy the file for the extension into your theme. If you are using Belgv facebook free the name might be facebookfree for template folder and facebookfree.xml for layout.

I am assuming you might have installed Belgv facebook login extension. YOu are not able to see the facebook login button because you haven't copied the template file to your theme rwd.

1. Goto design->frontend->default->Layout and design->frontend->default->template

2. copy the file for the extension into your theme. If you are using Belgv facebook free the name might be facebookfree for template folder and facebookfree.xml for layout.

[EDIT]

If the above solution doesn't work. You can add the code below in customer/form/login.phtml

<button type="button" title="<?php echo $this->__('Sign in with facebook') ?>" class="button fb_button_ps signface-btn" onclick="return fblogin();" ><span><span><?php echo $this->__('Sign in with facebook > ') ?></span></span></button>