Looks like Microsoft recently added a Large (A3) machine with 7GB http://azure.microsoft.com/en-us/pricing/details/virtual-machines/
How can I add memory to an Azure virtual machine?
Question
Is it possible to add a "custom" size memory to an Azure virtual machine?
For example, I'm using the Medium size - 2 core, 4GB RAM, I would like to have 8GB RAM with the current settings I have... otherwise the next option available is A5 2 core with 14GB.
Solution 3
OTHER TIPS
At https://portal.azure.com/ you can select the machine, then go to Size and pick another size for your virtual machine. It currently looks a bit like this:
If you scroll down see you a lot of different configurations, but you can't customize parameters of any of the given configurations.
See also How to: Change the Size of a Windows Azure Virtual Machine at MSDN.
Simple answer is you can't. You will need to pick up from one of the existing VM sizes.