You can paste the following code in the custom CSS box in the Design tab of your form editor:
.formz-container {direction: rtl; text-align: right;}
Add space between the checkbox & options in the multi-choice field:
.form-checkbox-input .formz-checkbox-label .formz-label-text { margin-left: 0; margin-right: 10px;}
Add space between radio buttons & options in the single-choice field:
.formz-radio input[type=radio]+.formz-radio-label:before { margin-left: 10px; margin-right: 0; }
You can also use this RTL template and customize it to your own.