effmrrt,
The best references for Newport feet and legs that I know in addition to the ones already offered are:
1) Master Craftsmen of Newport by Michael Moses
2) John Townsend Newport Cabinetmaker by Morrison Heckscher
3) American Furniture in the Metropolitan Museum of Art Late Colonial Period by Morrison Heckscher
These are out of print books and may be difficult to acquire, but they may be at a library. Don't forget to investigate the reference libraries at art museums. Also, I have not checked it out thoroughly, but you might want to look at Yale's Rhode Island Furniture Project for details. PSP