The option to inject on both the Install (primary) or Flash (MultiRom) screen should be checked/on for normal usage, it then avoids any manual injection.
If you'd be using F2FS, then it may
become necessary to explicitly flash a kernel with F2FS-support directly after the rom (personally using Tyr kernel by @DerRomtester
). If the rom does not support this scenario, phone will only show the 1+1 logo and stay there because in the background it was not able to mount partitions.