The 26-year-old centre forward spent the first half of last season on loan at Empoli and the second half of the season with Sampdoria, managing only two goals throughout the campaign.
Rangers boss Michael Beale wants to rejig his forward department and he snapped up Lammers from Atalanta on a four-year deal.
Former Netherlands international De Boer pointed out that Lammers was considered one of the brightest talents at PSV Eindhoven during his academy days and believes that the Rangers new signing has a lot of quality.
However, the former Gers star is unsure whether Lammers will be able to meet expectations at Ibrox next season and stated that he would not be betting on his countryman to be successful.
“Sam was one of the biggest talents at PSV Eindhoven and he has a lot of quality”, De Boer told the Daily Record.
“But can he do it?
“He has the potential but I wouldn’t put money on it.
“With him I still have a bit of doubt.”
Rangers are still in the hunt for another striker in the transfer market and they have failed with an offer for Feyenoord’s Danilo.
