How To Extract Column Numbers From One Cell

I a simple macro below that loops through columns and copies a value from each column. The columns to loop through are specified in cells F2,F3,F4 which contain numbers indicating the column number (currently 1, 4 and 7).

Sub Testing()
'For i = 2 To 4
Cells(6, i).Copy
Range("h100").End(xlUp).Offset(1, 0).Select
Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
:=False, Transpose:=False
Next i
End Sub

However, I would like to specify the column numbers in one cell instead across multiple cells. So, for example in cell H2 I could specify each column number separated by a comma
i.e. H2 would show: 1,4,7

Is there a way I could get the macro to reference that once cell only for the column numbers instead of in separate cells as currently? I'm assuming I need to use some clever text functions to extract each column number from the cell based on the comma delimiter and then feed into the macro?