My association always does this, but I'm not sure what the response rate is. Often the coaches/managers mention the opportunity to the parents/players. The league gives the blank forms to the team managers to distribute to the parents. The managers can collect them or there is a drop-off box in the rink, either way you can put it in a sealed envelope as they leave it up to the parents if they want to complete anonomously or put their names on the form. There is also a section for the player to complete or for the parent to ask the player what they liked/didn't like and write in their responses. You can also write comments about other team staff and about activities.
It's done near the end of the season. As far as I know, the executive actually do look at them and provide a summary of feedback to the coaches, but I'm not sure if the coaches have to request it or not. I think it's along the lines of 'no news is good news'. There have been a few times where if there are enough negative comments, or a consistency in negative comments then the following year the coach doesn't get a team.
I'm on the board for my son's club. We sent out evaluation forms via email at the end of last season and received 1 back and we have about 70+ kids on 5 teams. I think we would get more of a response if we did paper forms which were handed back in to the team manager. You're really only going to get responses from those who are unhappy, but most of them won't do it if its not anonymous.