The Dark Blues' title hopes were dashed by consecutive losses to France, second in the world rankings, and Ireland, the number one side.
Scotland started the Championship with wins over England and Wales and a further victory in their tournament finale against Italy at Murrayfield on Saturday would likely secure a third-place finish for the first time since 2018.
"I outlined our goal of five good performances and I think we're at three and a half just now," Ritchie said on Friday.
"To get it up to four and a half would be good so we're looking for a strong performance. To secure that third-place outright would be a positive."
The 26-year-old Edinburgh flanker added: "We shouldn't change our application based on the opposition. For us it's about maintaining the same standards and trying to put out our best performance, which I don't think we've done yet."
Italy have lost all four of their matches so far this year but Ritchie said their performances were better than their results.
"They'll be frustrated that they've played a lot of really good rugby and run a couple of good teams close but not converted that into results," he said.
"They come here with nothing to lose. They're always a passionate team but there might be a little bit more passion because they enjoy playing against us, they target this game."
Scotland will be without experienced backs Stuart Hogg and Finn Russell after the pair suffered injuries during last week's defeat by Ireland, with Ollie Smith deputising for Hogg at full-back and Blair Kinghorn taking over from Russell at fly-half.
"Although the changes have been enforced, that little bit of new blood and new energy into the group from guys who have been chomping at the bit for an opportunity is just what we needed in that short week," said Ritchie.
