Define dynamic data range

Hi,
I want to replace the hardcoded data ranges in my macro recording (shown below) with dynamic data ranges.

    Range("C2").Select
    ActiveCell.FormulaR1C1 = "=COUNTIF(Sheet1!R2C8:R168C8,RC[-2])"
    Selection.Copy
    Range("C3:C105").Select
    ActiveSheet.Paste

a) My active worksheet has an unknown 'n' number of rows in column A from row A2 onwards.

b) Column C2 contains a COUNTIF formula on A2 using data from Sheet1, column H rows 2 to 168. Sheet1 row H also contains an unknown number of rows from H2 onwards.

c) For every row in the range A3 to A'n' the countif formula in C2 is then copied its corresponding range (C3 to C'n').