How to keep page size when converting pdf to image

Question

I mainly use photoshop to touch up forms I am going to serve to users. Often these forms come in pdf form with a footer.

 1) I pull the pdf into photoshop, and select a page. 
 2) I then select a page, eg page 1
 3) Add new layer
 4) Move layer to background -> flatten image -> export as png
 5) do for each page in pdf*

Typically, these forms have a footer or border which forces photoshop to recognize the item as a full page. But, I am now encountering an issue where photoshop is not recognizing it as a full page, and the layers I am adding are only for the small blurb of text. When this gets exported to a png, it loses it's size dimensions for programmatically serving the image.

How do I select a pdf page and have photoshop see it as a full page (dimension-wise) and save as a full page with trailing white-space?

Example of the small area I am trying to force to a full page.

And this is an example of a full page and how it normally pops up for me.

I'm not sure how to 'search' on what to do Can't I change something here?

Answer 1

Instead of using photoshop, use adobe acrobat dc. Select export pdf as image. Select your file format i.e.PNG, check the export all images box. Select your destination path and click on export. See this screenshot for reference.

Answer 2

Photoshop doesn't care a bit for page sizes; it's just not designed that way.

Try starting with a default document the size of your intended output & placing the image on that. It should then preserve whitespace.