using simple fields in my rss feed

i’d like to display some simple fields i’ve created in my rss feeds, to use them in an automatic newsletter sent with mailchimp.

i already use my simple fields on my website, to display informations about my events (date, time, and location), for example on that page :
http://cluster015.ovh.net/~englishcy/category/events/

but i don’t find how to use these same simple fields…
i found that code, but i don’t know how to customize it to use the simple fields i’ve created : http://www.paulund.co.uk/add-custom-fields-to-rss-feed

thanx in advance for your answer !

http://ww.wp.xz.cn/extend/plugins/simple-fields/