Printer setup for borderless prints
I'm using an R3000 and I don't like the auto expand because it won't tell you exactly how much its going to scale up the image. I'd rather precisely choose my overbleed.
Normally I print borderless in Lightroom, but this should work in photoshop if configured the same.
When you pick the "retain size" paper size, it essentially tells the application that the page is bigger than it really is. So 8.5 x 11 becomes 8.7" x 11.27" and the application thinks that it's printing to paper that size, but in reality the printer is essentially "cropping out" the 8.5x11 rectangle in the middle of that. So you adjust the scaling in the application to give it a bit of an overbleed. For example, change the canvas size to 8.7" x 11.27" or whatever selecting the thing to keep the image in the center. Then either expand the image a bit to make it 8.6 x 11.1 centered in the canvas, or use the clone tool or something to clone some bleed.
I think in photoshop you'll have to:
-Click "Print Settings"
-Change the paper size to the appropriate "retain size" one
-Look above the preview area to see what your paper size is.
-Hit "Done" (not "Print")
-Enlarge the canvas to at least 0.1-0.2" greater than the real page size in each dimension, tell it to center the original image in the canvas, and set the expand color to white.
-Do whatever you want to scale/clone/edit the image so that it will bleed over the edges just slightly and make that white border go away. 0.1" on each side should be enough but I think I usually do fine with 0.05" around the edges. It just needs to be something more than zero in order to avoid a white hairline on some edges.
There's also a "Bleed..." setting in the Output (upper right popup in print) but I'm unsure of exactly how it works.