Fwiw Nate Silver's polling average sees RFK's effect as helping Trump by only 0.3%.

FiveThirtyEight's polling average for reference sees RFK's effect as helping Trump by only 0.2%.

His polling was on a downward spiral for the last few weeks.

So it is probably best to assume his effect is overstated.

Also he is going to try to remove his name from 10 battleground states, but it is too late for a number of them, so his plan may yield mixed results. Which again should attenuate his effect on the race.

As I mentioned before a lot of his voters are low engagement voters in polling (they don't vote regularly). So it is a pretty good bet a lot of them will just stay home now that he is out of the race.

They tended to not like Trump or Harris. I'm skeptical this endorsement will suddenly change that significantly.