Drag-out a box around the area you wish to become a hyperlink. You can resize this box after it's initial creation so you don't need to get it right first time.
After drawing the hyperlink box, the Link Properties dialog box is displayed.
Change the Link Type: to Open File
Enter the file-name in the File: edit box or press the Browse... button.
Choose if you want way you want the file to be opened with the Open In: pop-up. This preference is not used by Infix Pro PDF Editor but may be by other PDF viewers.