Reverse charge mechanism

Kindly provide a bit more clarity on the query..

If my supplies attracts RCM where my recipient is liable to pay GST. I am still required to issue GST invoice and mention 'Yes' in the filed ' whether liable under RCM'.. 

Suppose we are receiving a donation for making a construction for poor people & donor is asking GST invoice.Charity is not coming under GST ,so we can't issue the GST invoice. IN this case can we inform the donor to provide the donation after deducting the GST amount & pay the amount under RCM. Both the parties are GST registered...