当您想要在国外餐厅预约时，您可以使用以下表达：

预约用餐

"I'd like to make a reservation."

说明人数和时间

"For how many people？"

"When would you like to come？"

指定座位要求

"Non-smoking, please."

"We'd like to sit by the window."

特殊场合

"It's my birthday."

"We're celebrating an anniversary."

提供姓名

"The reservation is under the name of."

"My name is."

询问是否需要正装

"Do I need to dress up？"

结束语

"Thank you for your help."

请确保在预约时提供所有必要的信息，以便餐厅能为您安排合适的用餐体验。