You will find the answer in few of the document1, Document2:
1) In order to apply SQL Server transactional replication/publication, is it mandatory that all the tables selected in publisher to have a primary key ? Yes it is mandatory
2) Incase primary key consists of 2 columns, will transactional replication/publication work for that table? Yes the composite primary key is okay but the table should have a declared primary key
3) While applying transactional replication/publication what is the maximum no. of tables that could be selected as articles for publishing?
4) Could you please provide me with limitations of transactional replication/publication? The documents have some remarks and limitations. Please check.
Please let us know if you have any questions.
Regards
Navtej S