Richardson (6-6, 319) has played in 32 games (17 starts) in three campaigns with Kansas City (2008-10). He started all 16 games a year ago, 15 at right tackle and one at left tackle. He entered the NFL as the first of Kansas City's two selections in the sixth round (170th overall) in 2008.
Richardson appeared in 49 contests at Clemson, starting 46 games. He was a three-year starter at Wando High School in Mt. Pleasant, S.C.
The club also announced the signing of free agent LB Brandon Siler.
Siler (6-2, 239) has played in 58 regular season games (12 starts) with San Diego (2007-10), recording 124 tackles (89 solo) and 3.0 sacks (-26.0 yards). He also has two interceptions, four passes defensed, one fumble recovery and 56 special teams tackles. He has appeared in five postseason contests (one start), compiling six tackles (four solo) and nine special teams tackles. He entered the NFL as a seventh-round selection (240th overall) of San Diego in 2007.
The Daytona Beach, Fla. native was a member of the University of Florida squad that won the 2007 BCS National Championship Game. Siler was named second-team all-state at Evans High School in Orlando, Fla.