I would put it on within my program folder, add a link within my Start Menu folder to allow a direct access (without starting my tool) and just at on some click event System.Diagnostics.Process.Start(@”.\Manual.pdf”);
Ok, now we come to a completely new question: How to embed a file in my application and start it?
For this question you’ll find already several answers here, but here is the short version:
Right click your project and select Add – Existing Item
Select your file (don’t double click it)
Click the little arrow next to the Add button and select Add As Link
Double click on Properties – Resources.resx
Click the little arrow next to Add Resource and select Add Existing File
Select the same file again in the open dialog
Now you can access the file within your code as byte from Properties.Resources.NameOfResource
With these steps you reference your file where ever it exists within your structure. If you like that a copy of your pdf file will be put into a subfolder Resources within your project, just skip the points one and two in the above list.
To get your pdf now opened, you’ll have to write the byte down to disk (maybe with Path.GetTempFileName()) and start it with Adobe Reader. (Don’t forget to delete the file after usage)