It is my understanding that the photographers who post their photos in the RIL have given permission to Wet Canvas members to use the photos as references. However, they still retain the copyright for the photos themselves.
Since this is going to be published in a magazine feature, I would err on the side of caution and wait until I received permission from the photographer before reproducing it in the magazine. This is just my personal opinion though, so it might be good to hear what others think as well.
BTW, CONGRATULATIONS on being asked to do the feature showing a demo of your work. That's really good news!