summon marker with rotation

I want to summon a marker at every player with the rotation of the player it was summoned on and a custom tag. My current approach is the following:
execute as @a run function summon_marker
function summon_marker:
tag @e[type=marker,tag=] add shuffle```

How do i get this to work? Currently i don't know what target selector i'm supposed to put in the `<player>` place.