Logrotate parameters of .conf file

Hello there,
I’m setting up the rotation of the systemLog file.
I would kindly ask what are the parameters that I can set to have a suggest size of a single log file and how many days to keep in order to have enough log to take a look.

I’ve found some examples of .conf of logrotate where almost all include the following: kill -SIGUSR1, some others, doesn’t include it. It’s absolute needed to include or not?