There is no Roosevelt Island F Train service to Manhattan this weekend. According to the MTA:

SIGNAL IMPROVEMENTS 11:45 PM Fri, Oct 19 to 5 AM Mon, Oct 22 Coney Island-bound F trains run via the E from Roosevelt Av in Queens to 5 Av/53 St in Manhattan

Trains resume regular service at 47-50 Sts.

No Coney Island-bound service at 21 St-Queensbridge, Roosevelt Island and Lexington Av/63 St.

Travel Alternatives:
For service to 21 St-Queensbridge and Roosevelt Island, take the F to 47-50 Sts and transfer to a Jamaica-bound F.

For service from these stations, take the F to Roosevelt Av and transfer to a Coney Island-bound F….

Also:

… STATION ENHANCEMENTS | Until December 2018 57 St F Station is closed…

Both Tram Cabins operating at full capacity. There is Roosevelt Island ferry service on the Astoria Route. Here’s the new Fall Schedule for Roosevelt Island ferry service.