Jude,
If *nothing* is appearing in the activity stream, then something strange is happening. My guess is that you're editing the wrong template file. You can test by updating the code you're adding to:
TESTTEST {JFBCLike show_send_button=false href=<?php echo str_replace(JUri::base(true).'/', '', JUri::base()) . CRoute::_('index.php?option=com_community&view=profile&userid='.$act->actor.'&act='.$act->id); ?>}{SCGooglePlusOne}{JLinkedShare}{SCTwitterShare} TESTTEST
If you can't see the words TESTTEST TESTTEST in the activity stream, it means you're in the wrong file. Please make sure that you're editing the proper JomSocial template file that you have selected in JomSocial.
If that doesn't work, or you do see the TESTTEST output, let us know a page where we can see the JomSocial activity stream and we'll gladly investigate what's happening on-page and determine why it's not displaying properly.
Thanks,
Alex