As far as I understand, you mean that your splitter is 100% high and you want to have also a top and bottom logos. If so, you can use one of the following approaches:
1) Set explicit pixel height only for the logos and then set the HeightOffset
property of the splitter to the sum height of the logos - this will force the splitter to automatically calculate its size to be always 100% of the remaining space on the page except for the logos, no matter of the resolution.
2) You can use two additional RadPanes - one on top and one on bottom to put there the logos (you can use nested splitters for example if needed).
I hope that my suggestions are helpful, in case you need further assistance, please share some relevant code with detailed explanations and I will help you achieve the desired result.
the Telerik team