Adding the following to your template's CSS file should do it for you. Any CSS file that's loaded on the page should work, and most templates have a file just for users to edit:
It's up to you where it goes. It can go in the JLinked.css file, but that will be overwritten as you upgrade JLinked. However, each template may need a slightly different margin since each template will display the article differently. So, it's likely best to put it in each template so that you have more control over that look for each template.
I've tried this code in both the template.css file and the thirdparty.css file, and neither affects the change.
I've posted in Rocket Theme's forum (private) to ask advice there, so we'll see if anybody figures out how to fix it. Will post back here when one of their CSS gurus schools me up.
I actually see the change in the thirdparty.css file. If you increase the margin to 50, you'll see a difference. 25 is just too small for the height of the buttons, which are done through Javascript, so height gets a little funky.