Hi,
Yes, there is a way to schedule recurring activities to appear on someone else's calendar.
To do so you'll need to open a new activity and fill out the info under 'Add/Edit Activity' - here you'll select the person that the activity should be assigned to. Please note this activity will be the series, think of it as the parent and then you'll have the monthly occurrences - the children. So the date you choose for this activity should probably be the last date - reason for this is because if you update series then all the occurrences would be updated, unless they have been edited already.
The next step is to go to the 'Recurrence Info' tab link and check 'Recurring' then fill out your preferences then click on update and close out of the window; by doing this you create the (monthly) occurrences in your case. You can verify the activities have been added by changing your filter by view to 'All Activities'.