How often do I rotate the tires on my 2016 Outback

I usually have this done every oil change. It's easier to remember to do that... Your call.

YOU should rotate your OBs tires as a function of both they're tread pattern (to prevent scalloping) and mileage extant (to prevent asymmetric wear). Generally every 1-2 years is sufficient, smaller weight imbalance with the OB doesn't force frequent rotations, unlike FWD vehicles. But if you particular tire model is subject to early scalloping then CROSS- rotate (if non- directional... and possibly rebalance) immediately followinbg with one final rotation later. If scalloping has progressed to the point of excess noise wait a few k-miles to see if they've self-corrected. If not, you'll have to buy fresh tires. Some tires (the old Subaru OE BS RE92A are famous) NEVER scallop, and thus require only one rotation in their long lives; others...particularly some asymmetrics, scallop within 15-20k miles, requiring annual rotation to keep reasonably smooth and not excessively noisy. Among the worst were the BS G009 and G019 that BS developed to improve winter traction over the much nicer RE92A. So have a tire guy show you in 10 seconds how to "feel" your tread wear to see if rotation need is imminent because of scalloping. If not, rotate when fronts are down about 2-3/32" (20- 30%) compared to rears. Note that rears AlWAYS scallop first...which most folks find a bit ironic. If your tires are asymmetric tread pattern note also that you CANNOT cross-rotate in an attempt to correct minor scalloping, and have to simply hope that a front-back rotation will quiet down the tread...but it's usually unsuccessful, and why I don't recommend asymmetrical tires for casual owners. In exotic apps it may be worth "flipping" the tires (inside-out) in order to save scalloped expensive summer rubber. Your Limited fortunately sports 60-series 18's...take care of them...but don't rotate excessively, as the risk of a wrench cross- threading or not torquing a stud correctly of course increases with frequency.

they're=their (sigh...)

I rotate my Forster's tires every 6,000 miles.

it's recommended 6-8,000 miles

"Recommendations" in OMs are just dumb centrist guesses. See above.