Making a date in RSS feed comply with W3C and show the time in my timezone

Hi,

I need to properly set up a date for an RSS2 feed, and every time I try something, there is always an error, according to W3C…
https://validator.w3.org/feed/check.cgi?url=http%3A%2F%2Fwww.gamekeeper.ca%2Ffeed%2Fai1ec_event%2F
Right now, I have it set up as follow: D, d M Y H:i:s T

Furthermore, my time is not properly set…. It should be UTC -4, but I always get the UTC time. I absolutely need it to show my timezone time.

I kinda know my way around PHP, but I am definitely not an expert, so anybody willing to give me details on how to achieve this, I would really be grateful!