weighed Fleming-Harrington log rank test

You are correct that the survreg routine only supports 'rho' of the Fleming-Harrington G-rho tests.  This is a function of age -- I wrote the original code back when I was working with Tom (Fleming), and he was only using 1 parameter.  Later he and David expanded the test to two parameters.  This might be only the second request for the feature in the 30+ years since that date.

Terry Therneau