Of course make sure settings are correct in global parameters of K2.
Have the rss display for the particular category you want.
Click it. Make sure the url ends in ?format=feed
If it doesnt, with that.... hmm. Dont know how to fix that.
Try validating it here:
feedvalidator.org

If it doesnt work, go to admin>global config and turn of gzip under server. That very well may fix the issue. Did for me.

Can anyone advise which file I can edit to remove the author email from showing in the feed. This is a privacy issue for my site.

<author>emmy#$#$&@yahoo.com (Emmy Lindgren)</author>

Id prefer it simply be the username displayed as Author or at least NOT show the email.

Hello Shonn,

Simply edit the RSS Feeds settings. They are located under K2's params and the content tab.