'd rather 是had rather的缩略形式,意思是“宁可/宁愿”,后面跟宾语从句,表示主语个人的意愿.这是一种虚拟语气,动词要用相应的过去时态.
本句的结构如下：
主句：I had rather
宾语从句：the job was more that I could do myself 其中——
【主句】the job was more
【定语从句】that I could do myself
这句话的意思是“我宁愿我自己做的这件工作更多一些”.
类似的用法还有 ‘d better (had better),后面跟虚拟语气的宾语从句表示主语的意愿,意思是“希望某人最好去做某事”.