Not always. If you inject feedback into an experiment, then yes, the experiment becomes biased due to your intelligent intervention (ergo, intelligence is indicated).
On the other hand, feedback can exist naturally (speaking broadly).
Speaking on the more narrow topic of this thread, I'm unaware of any scientific evidence that we might have that would indicate that a specific natural feedback mechanism was active in sequencing the first DNA bases, however.
Suppose we have chemicals A, B, C, D. In the initial 'round' of reactions we get relatively simple compounds AD, BC, etc. Feedback occurs when these simple compounds are used as 'inputs' to further reactions to create more complex compounds ADBC, etc. Are you saying there is no evidence for this?