Hi there, and welcome to the board!
I use a Windows API call to do this. This code goes at the top of your module, after any option lines and global variables, but before any subroutines or functions:
You'd then call this as follows:
Private Declare Function ShellExecute _
Lib "shell32.dll" _
Alias "ShellExecuteA" ( _
ByVal hwnd As Long, _
ByVal lpOperation As String, _
ByVal lpFile As String, _
ByVal lpParameters As String, _
ByVal lpDirectory As String, _
ByVal nShowCmd As Long) _
In this case, sFilename is the path, name and extension of your file. You don't need to tell it which application it is, as the ShellExecute API uses windows file association to figure that out for you.
ShellExecute 0, "Open", sFileName, "", "", 1