If i baited hook rift herald, then rift herald death knell ability will resolve first putting a unit to base and then i will look at top 5 of my deck. Is that correct?

No — the order is backwards. Deathknell resolves last, not first.

Here's what actually happens: when Baited Hook resolves, it kills the Herald and that makes the Deathknell trigger a pending item on the Chain before the Kill instruction completes (Rule 808.1.d.2). But Baited Hook keeps resolving — you look at the top 5 and may play a unit. Only after Baited Hook is fully done does the Chain resolve in LIFO order, so the Herald's Deathknell trigger resolves afterwards, letting you play a unit from hand to your base. (If the unit played off Baited Hook has a "when you play me" ability, that resolves before Deathknell too.)

So the sequence is: Baited Hook finishes (top-5 reveal/play) → then Rift Herald's Deathknell puts a unit to base. The Deathknell unit goes to the trash first, but its effect waits its turn on the Chain (Rules 340.1, 808.1.d.2; FAQ #9826).