How to add multiple photos to one page and be able to custom size them

First, you can crop pictures within Photos and, since Photos is uses non-destructive editing, you can undo the crop later. Another option is to duplicate pictures (command-D) and to work on the copy.

To print, try command-P, and choose Contact Sheet. If you want, you can include titles and dates and other information with each picture.

You can adjust the sizes of the pictures on the page by changing the number of columns. I've used 3 columns on US letter paper in the example.

Even though your are in the print dialog, you don't have to actually print this page. You can save it as a PDF by continuing with the print command, and you'll see a pull-down menu in which you can choose PDF.

You can also use the Preview app on your Mac.

Take a duplicate of any random photo, open it in preview, and do an Edit/Select All, Edit/Delete. That leaves you with a blank transparency screen. With the transparency screen open, open any other photo and do an Edit/Copy and then Edit/Paste it into the transparency screen. You can do this repeatedly with several other photos and position and resize them as you wish.

-- Rich

You are welcome. I have found the Preview transparency screen option to be very helpful on occasion when I need to design a collage or other layout.

-- Rich

Your best bet would be to use Pages, the free app from Apple's App Store.

Setup the page size you want, add the photos and resize and move to where you want them . I used Pages to create this 20" x30" college:

I created a custom page size, added the photos, reside and placed them.

In Pages you can click and drag an image to resize and to drag to a specific location.