If the targeted creature is an illegal target when Rite of Replication tries to resolve, it won't resolve and none of its effects will happen. You won't create any tokens.

Each token copies exactly what was printed on the original creature (unless that permanent is copying something else or is a token; see below). It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or any Auras or Equipment attached to it, or any non-copy effects that have changed its types, color, power and toughness, and so on.

If the copied creature has {X} in its mana cost, X is 0.

If the copied creature is a token, the new token that's created copies the original characteristics of that token as stated by the effect that created the token.

If the copied creature is copying something else, then the token enters as whatever that creature copied.

Any "enters" abilities of the copied creature will trigger when the token enters. Any "as [this creature] enters" or "[this creature] enters with" abilities of the target creature will also work.

The tokens see each other enter. If they have a triggered ability that triggers when a creature enters, they'll all trigger for one another.

If a spell's kicker cost was paid, the spell is "kicked."

The kicker ability doesn't let you pay a kicker cost more than once.

If you put a permanent with a kicker ability onto the battlefield without casting it, you can't kick it.

If you copy a kicked spell on the stack, the copy is also kicked. If the copied spell is a permanent spell, the token the copy of that spell becomes when it enters is also kicked.

If a card or token enters as a copy of a permanent, the new permanent isn't kicked, even if the original was.

To determine a spell's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases (such as kicker), then apply any cost reductions. The spell's mana value remains unchanged, no matter what the total cost to cast it was.