If you don't have a copy of Acrobat, you can merge PDF files online for free using PDFMerge and Merge PDF.Click "File" on the main menu in Adobe Acrobat XI, select "Create" and then click "Combine Files into a Single PDF" to launch the Combine Files dialog.I've done the same thing but the resolution is very low.While viewing the PDF document at 100%, edges of fonts as well as images is grainy and not sharp.Click the "Choose File" button and select the first PDF file you want to merge.Repeat this step for each PDF file to include in the final merged document. Click the "Merge" button to merge the files into one PDF document.You can merge multiple PDF files into one document if, for instance, your scanner produced individual pages of a document while scanning, or you have multiple documents that would just work better as a single file.Take advantage of the Combine Files tool in Adobe Acrobat XI to merge existing PDF files.
You can also select the Combine Files or Organize Pages tool in the toolbar to add more pages.
To insert each pages, open your first PDF file, and then use these keys at the same time: Command Shift I A window will open and you can select all your files you want to insert.
To move an entire document into another PDF, you can also drag the document's icon from the Finder into the thumbnail pane of a currently open Preview window.
Generally I wouldn't create pdf's in photoshop unless I have to. If I'd have to, I'd use text layers and shape layers to maintain scalability in the pdf.
You can simply use Adobe Acrobat Pro that comes with the Adobe Suite/Cloud, and "insert" your pages in one document.