Foreign pension from Germany (the federal state of Germany) - on what line do I need to report this ?

You will find that the gross amount goes to,line 115.
You should enter the gross amount through Foreign income, enter the exempt amount, then claim a Foreign Tax Credit fornthebtax paid in Getmany

I see where to input the gross amount but am unable to find where I enter the exempt amount

Look for the entry box 'Pension exempt under a tax treaty'