How to disclose Outward RCM supplies in GSTR-1 & GSTR-3B of tour operator service

I have a query on how to disclose RCM of outward supplies in GSTR-1 & 3B. Q1) In GSTR-1 B2B column RCM invoice value should be shown in O% row or 5% row. Q2) In GSTR-3B outward RCM turnover if we shown in 3.1(a) it will ask to enter tax amount compulsorily so we cannot show in 3.1(a). So my question is in column 3.1 where the RCM outward supply to be shown.

Kindly suggest

Thanks you