Steps:
1. Go to Library --> Machines.
2. From More options drop down select "Add" option.
3. Enter the name of the machine
4. Select a Template machine to add.
5. Template machine is listed in Library --> Machine.
6. Deploy the template machine.
7. Go to Deployments --> Machines.
8. From the Ops menu of the template machine select "Edit Config" option.
9. Change the count for vcpu
<domain type='kvm'>
<name>291efe8b-a311-4eca-8a34-abe302c804a0</name>
<uuid>291efe8b-a311-4eca-8a34-abe302c804a0</uuid>
<memory>10240</memory>
<currentMemory>10240</currentMemory>
<vcpu>Enter the count for vcpu</vcpu>
10. Click on the "Save" button.
11. Now you can start the installation process.
NOTE : It is necessary to allocate vcpu support to the template machine before starting the installation.
(For eg: Ubuntu server installation etc)