uea推荐信的问题请教

uea的application form 附的推荐信表格很奇怪，要回答很多问题
a。 ability to gratp concetps and reason analytically
b. ability to use mathematical and/or statistical techniques:
c. motivation and perseverance in achieving objectives:
以上问题都有百分比的选项
而且还要盖上： official stamp（官印？）
“please not that references will not be acceptable unless they bear the official stamp of the university or other institution at which the referee is employed." (原文）
这样的话岂不是不能自己写完推荐信然后直接给教授签名了？可不可以自己做，有哪位uea的前辈能帮忙解答一下，多谢