The following shows the set-up for a charge type that will on-charge GST inclusive amounts entered to a client.
'Use Charge Rate From' is set to Fixed, with a fixed rate of $1. This is because the amount to be charged will be entered. The Units are set to $ so when entering expenses through time sheets, the $ amounts will be prompted for.
You could potentially set up a Work item for expenses and Work Categories under that for different types of expenses. You could then include the [Work Category] merge token in the Invoice Line Narration so the expenses are broken out in the invoice.
To add an admin surcharge onto the expenses charge you could set the Rate Multiplier to, for example, 1.1 for a 10%.
Ticking GST Inclusive means that GST inclusive expense amounts can be entered, which is typically easier. When the invoice line is generated the rate will be converted to the GST exclusive amount, so a rate of $1 will get changed to $0.8696. Showing this rate on the invoice is unnecessary and would add confusion so Show Rate and Quantity has been unticked to exclude them for these lines.
The Sort Order is set to Second so that the expense amounts are shown after the regular charges in the invoice.