How do you combine multiple photos into one PDF file using PSE 14?

I dont know why others havent mentioned it, but there is a much simple way is most of the recent Photoshop versions.

1. Open photoshop > Files > Automate > PDF Presentation.

2. Select the images from the window in the order you want the pdf to be created. (All pages can be selected together by pressing Cmd or Cntrl, but click on first page image first, second page image then, like that. Alternatively, rename the pages in order, then you can select all in one go.

3.Select the output option as multi page document instead of pdf presentation. 

4.Click save, and add choose the location you want to save the document. You can add document details like author, name etc here. Also you can choose background color, compression methods etc.

Thats it, as simple as that..photoshop will open these images and close them. Then you can see the pdf saved oin the location preferred. 

You can also create multipage pdfs from the 'Share' panel, with 'email' and 'pdf slideshow'. Those are available in recent PSE versions, I think they are available in  PSE14.

It looks like Adobe is limiting severely the ability to manage pdfs from Elements and hopes you to subscribe to Acrobat.

A little known fact about pdf formats is that the usual Acrobat/Illustrator format is no longer supported in recent Organizer versions. Only the 'Photoshop pdf' format is supported for your catalogs. That format combines a plain Acrobat pdf with a full psd format (even with layers). The good things are that the files open directly in the Acrobat Reader and in the editor while being managed in your catalogs. The bad thing is that the format creates huge size files.

I'd say that most Elements users won't subscribe to an Acrobat plan just for a few creations. So they are tempted to go to the competition. The usual choice is to download a free 'virtual pdf printer driver'. This software installs a printer driver which creates a pdf file instead of printing from your printer. You 'print', you don't 'save as'.

Beware of many free drivers, you don't know what kind of malware/addware may be hidden...

My choice is to use the Microsoft 'Print to pdf' driver installed automatically with Windows 10. I believe you have similar tools for Macs.

If you are interested by more pdf features, you might consider the open source softwares Scribus or Inkscape (similar to Indesign and Illustrator).

Are you saying that you want to create a photo collage on one page as a pdf file or do you want to create a multi-page pdf file with different photos on each page?

If you want to create a single page collage, simply save the file as a pdf, by using the drop down menu for Save as type:

If you want to create a multi-page pdf, I think you will have to create a photo book and Print it to the Auto Adobe PDF printer that I believe is included in Elements 14.