Go into Medium, take a few photos, find them in this area C:\Users\yourName\Documents\Medium\Photos\yourName and then open the .png files in Photoshop and replace the image with one of your reference images, save the file.
Now go into Medium and load your pictures. If you go in and inspect the photo you will get a larger view of the photo. You will have to use the red home button (my left controller) to pull up and take down the image.
I know this isn't a true way to view reference image, but it could help until the real deal comes along.