Table 4B. All outward supplies on which reverse charge is applicable and which has been excluded in 4A should be shown here like outward supply u/s 9(3) SGST/CGST
GSTR 1 is for outward supplies only. GSTR 2 is for inward supplies. It also allows for creating RCM liability and claiming RCM inputs. It has several tables for RCM Go and check GSTR 2 form and all doubts will get cleared. So no RCM entries in GSTR 1.