The full-back feels the former Manchester United forward will be vital in the Cottagers' bid to stay up, despite his lack of goals, and also praised coach Rene Meulensteen
The 32-year-old striker has scored just two Premier League goals in 13 appearances this season and has struggled to hit top form for a side that have slumped to 18th position with 13 points in 15 matches.
|4/1||Fulham are 4/1 with Bet365 to draw with Everton on Saturday|
And, speaking to the club's official website, Riether said: "He's our best player, no doubt. We need him to get out of this situation and in the last couple of games he's been fantastic.
"He did some important runs for the defence as well. He worked hard and tried his best for the team. If we have a negative run, the famous players get picked out. But he showed he wants to have success with the team and he gave everything."
Meanwhile, Fulham's performances over the last two fixtures will have impressed new head coach Rene Meulensteen, who replaced Martin Jol at Craven Cottage, with the 57-year-old paying the price for a run of five straight Premier League defeats.
Riether believes Meulensteen's presence has been very motivational for the Fulham squad.
"He changed different things but it's important we as players react on the pitch," he continued. "We know we have fantastic players but we have to show it on the pitch. If you haven't got a team you'll win nothing.
"When he speaks to the team, it's very good and very motivating. You can see on the pitch that everyone is fighting for him."
Fulham will look for back-to-back victories when they visit Everton on Saturday but have never won a league match at Goodison Park.