Which functions did you use: how to allow putting the layout on the selection screen and when user press F4 he will be able to use the list of layout he has save on the ALV output?

REUSE_ALV_VARIANT_DEFAULT_GET,
REUSE_ALV_VARIANT_F4,
REUSE_ALV_VARIANT_EXISTENCE,
REUSE_ALV_VARIANT_DEFAULT_GET
For F4 help: REUSE_ALV_VARIANT_F4