Resident FTC claim

dear all,
one resident client has got foreign salary income for one month in the previous year 20-21 for which employer hs gvn workings for tax relief under section 90.
now for claiming the relief i understand we have to file form 67 first and then ITR 2.
but do we need to file form 10f also? or do we need to get Tax residency certificate? pls confirm the procedure to follow in this case