When posting to /me/feed, it's possible to add a page id of location with "place". This results in a post as a check in that shows the message with a map of the location.
Adding "place" as a query string parameter to the feed form at facebook.com/dialog/feed doesn't seem to add the location to the post. Is there a way to use /dialog/feed and add a location?
After discussing on FB group, it looks like only message, picture, and place work to make a checkin with a location. If adding other parameters like caption or link, it turns into a regular feed post without a location. This is unfortunate because without a link back to the app, there is almost no incentive to make a checkin from an app.