You are trying to set range object to variable type worksheet.
Dim shttocopy As Worksheet
Set shttocopy = wkbSource.Sheets("sheet3").Range("F65:N89")
Change
shttocopy
variable to proper type, for example:
Dim shttocopy As Range
Set shttocopy = wkbSource.Sheets("sheet3").Range("F65:N89")
BTW: do not use macro! Reason is here:
6 Reasons Not To Use Excel VBA (Macros)[
^]. I agree with the most of them.