For standard resources in dialogs like the checkbox please use
In MFC StringTable resources that are internally organized in blocks with 16 entries you have to calculate the ID
If PslSourceString.ResType = "StringTable" Then
MsgBox "ID: " & ((PslSourceString.Resource.ID - 1) * 16 + PslSourceString.ID)
It is true that PslSourceString.Resource.IDName is empty in binary MFC and other resources, but when parsing the RC file this will be set with the mnemonic name from the RC file. The allows you to have both the numerical ID and the mnemonic ID.