How do you load resources easily other than adding one by one for each activity?

add roles to each activity in the planning process, so when it comes to assigning resources you won't have to assign resources to each single activity but you will assign resources to the roles and resources will come automatically under the activity

Thank you Binil for your valuable question and also thanks must be transferred to Mohamed for his good answer .
I would like to add another technique for the assignment of many resources to an activity is simply by using the copy and paste technique which enable you to assign many resources to an activity in one step and that will save time.
Thank you Best regards