I think I might have found a way. Is this following a valid way of doing
this?:

Declare

FontFamily[] ff = FontFamily.Families;

as a form member.

In form constructor populate combo box as follows:

for (int i = 0; i < ff.Length; i++)
{
comboBox1.Items.Add(ff[i].Name);
}

and then event in combobox:

richTextBox1.SelectionFont = new Font(comboBox1.Text,  comboBox2.Text);

Does the above present any problems I should know about?
Also, is there any way of making the first combobox element display as
default, rather than having to open the box up?

Any help would be greatly appreciated.

Chris