macro to check if a value exist in sheet and add it if it doesnt

Hi,

I need help from you experts on this problem I'm having:

I've attached a sample workbook with the post.

I need a macro to go through the values in column A in the "reference" tab and check if the value already exist in column B in "master" sheet. If it does, then do nothing for that cell and continue on to the next cell, if it doesn't exist then add all three values for that row (column A, B and C) to the end of the table in "master" sheet and then go to the next cell. Go through all the values in column A in the "reference" tab.

Please help.