For now, you want to mention @exifr in a comment (not a post). In the future, @exifr will support posts. Also, at this time, just the first photo will get exif data. Steem users thought it was too much spam. In the future, each photo will get exif data. Here's an example https://steemit.com/photofeed/@r351574nc3/drama-for-drama-sake

The second photo got exif data only because the first had no exif data at all. Each photo will get exif data. Sorry if this is confusing. To make it short:

1. Exif data in comments and only on one photo is how it works now
2. Next version will support @exifr in posts, data in posts, and all photos for the post.