Before creating a restore point on a primary database, not to break the standby, a few things must be done in a certain order.
#1 Stop the apply on the standby. Otherwise the next step will fails with ORA-001153
edit database <primary> set state='TRANSPORT-OFF'; edit database <standby> set state='APPLY-OFF';
#2 Create a restore point on the standby
CREATE RESTORE POINT RP_STDBY GUARANTEE FLASHBACK DATABASE
#3 Create a restore point on the primary
CREATE RESTORE POINT RP_PRIMARY GUARANTEE FLASHBACK DATABASE
#4 Restart the the apply on the standby.
edit database <primary> set state=’TRANSPORT-ON’;
edit database <standby> set state=’APPLY-ON’;