The 49ers on Monday placed running back Jerick McKinnon and rookie safety Marcell Harris on injured reserve. They signed offensive lineman Matt Tobin and defensive back Antone Exum Jr. to fill out the roster ahead of the season opener Sunday against the Minnesota Vikings.
McKinnon was sitting in a golf cart on the sidelines during 49ers practice Monday morning and appeared to be in good spirits after tearing his right ACL during an informal practice on Saturday.
Second-year back Matt Breida and veteran Alfred Morris are expected to fill in with McKinnon sidelined. Breida (separated shoulder) was back on the practice field Monday and is expected to play in Minnesota after suffering his injury in the first quarter of the preseason opener.