Miller, a tight end from Arizona State, came to terms with the Raiders late Friday night and was on the field for the team's first two-a-day workouts the following morning. His signing comes two days after Oakland released veteran tight end Courtney Anderson.
Terms of Miller's deal were not disclosed.
While Russell remains at his mother's house in Mobile, Ala., Josh McCown and Andrew Walter are splitting reps running Oakland's first-team offense in practice.
"He's still not here," Kiffin said. "(We're) still making movement on his contract but obviously not there yet."