I didn't see the original post but to use RowSource you just identify a string
that represents the address of the cells (see the help file, that's what it says
too). Attached is a .xls file with a simple form  with one combobox and one
listbox. Both have RowSource set to "TestData" which is a column of data on a
worksheet. If you're doing this in VBA instead of writing the name TestData
directly in the properties dialog then you need to include quotes around the
name.

The title of this thread is VLOOKUP but since the latest question is about
RowSource, I answered it based on that.