I 1st use a free action from Speed Scraps which takes the PSD and gives you a 3600dpi and a 600dpi (which I make 700dpi) jpeg. In PSE, I take the 6/700dpi image I and do what
@michelepixels does...but I do not have to change the height or width. There is a tiny Drop Down area at the top right. Use that.. N.b. This is defaulting to MY chosen size of 700x700 but TLP allows up to 800x800. Just a FYI.
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Because I'm on a new iMac, I find that if I add sharpening my layouts look over sharpened. I prefer to do that on photos in Lightroom before I scrap.