If you don't know that then I doubt you will be safe. You need to find a local forum member or someone else to help teach you basic stuff, any old fool can get a boat and head out to sea, but when the turn around or look back could lose sense of direction, you then just need some fog or bad weather or run out of fuel then you are in trouble, so do that FIRST.
For safety you need to ensure that the vessel is seaworthy as is the engine, if it is electric start have a good battery and a plan if the battery fails.
Have a second means of propulsion 1e.g. wing engine, oars
You will need lifejackets FOR ALL
Check the pressure of the tubes before you go out
Get a radio (if you have passed the course to use it and be licensed) or at very least a mobile phone in a 'waterproof cover' with the phone number of the coastguard logged in.
Tell a friend when you are going out, where you are going a a time you will be back, they they don't hear from you they will know something could be wrong.
Ensure that you have enough fuel and perhaps a little spare in another container, it is amazing how quickly it can run out and surprise you.
There are charts called 'tough books' I think, they are smaller sections of the coast in a waterproof format, but if you can blag a plotter even black and white all the better, but make sure you can understand it, same with the charts.
Have an anchor with a minimum of 2mtrs of chain for your size of boat and enough line for the areas you are visiting.
Take some basic tools and a torch
Take a spare line that can be used for towing or as a throw line.
Some smart phones have the capability for downloading charts, these are useful in an emergency as they will give you an idea of where you are dependent on the hardware you are using e.g. does it have built in GPS? otherwise it is done by signal triangulation not so accurate but not bad.
Make sure you have a KILL CORD, this will stop the engine if you depart from the RIB, if you don't the RIB could just circle around you and cut you up into pieces GET ONE!
Take some fresh water to drink and perhaps some carbohydrates in the event you need food for any reason.
Ensure you have the correct clothing for the weather, remember it can change quickly.
Flares if possible AND KNOW HOW TO USE THEM
That is a start, I am sure others will chip in, good luck and BE SAFE