Go to Tools | Customize… | General from the main menu bar, press the large Keys/Commands… button, pick a location in the Command Mapping dialog where you’d like to position the command (usually the area flagged for user assignments), and click the Insert button.
Create the new command Name: CMac User Guide Cmd Line: <comspec> /c start “” “<Me_Path>Doc\CMac User Guide.pdf” Type: Program
Then, click on the Program Setup dialog. Select the option Show: Minimized
Then assign this command to a menu or hot key. To assign to hotkeys, do that within this dialog.
To add it to the Main Menu,
go to Tools | Customize | Menus…
Select Main and choose “Edit”
I went down to the Help section and inserted my “Cmac User Guide” menu item and selected the CMac User Guide command I had just created.
Just OK out of the dialog and try it out!
Now, when I go to Help | Cmac User Guide and select it, the PDF file is called and opened. Voila!
This does assume that the PDF file is stored in the Doc directory of Multi-Edit. If not it must be moved there or the path in the command line changed accordingly.