OK, I can see the buttons now.

For example:
Karma: +22/-7
[applaud] [boo]
But, I question whether someone who has never posted is able to.
If that is not your intent, you may want to test it some yourself, or ask others here to respond if the problem is system specific. It is hard for me to believe you wouldn't want everyone to use this feature. Most people probably post at some point, but many don't. To me the results would seem a little skewed if they didn't include the entire audience.
More generally, I agree that you need some adjustments. It wouldn't be surprising though to see people with strong opinions to elicit both high positives and high negatives in any case. It can't be helped at times, but it also gets back to the idea of treating others with respect. It can give you an idea also of whether you are making a persuasive argument, but I hope people don't feel they have to think or worry about this feature too much.
Surely, most Cyclone fans have positive karma. ;D