A periscope was added to the Tiger's turret roof in March of 1943. This kit seems to offer you a choice, to have that periscope or not.
This is the kit's instructions. It states that the periscope cover, part C27, may be omitted.
But, if you omit the periscope cover, the turret roof still has these features molded into it: a trench and a protruding tab. The real Tiger had nothing at all here before the periscope arrived.
You can make a more accurate model by removing the tab and filling the trench in the roof. But really, if accuracy is a concern, you should not be omitting the periscope at all. It was introduced in March 1943, and this kit builds a Tiger of May 1943.