Cannot Print a 5.5 x 8.5 document drop down menu does not have this size

I a m trying to print an invitation that has a size of 5.5 x 8.5.  When you have to select a document size that size does not exsist nor does custom size exsist i  n the drop down menu when selecting the document size.  The document was done inMS word & when you do a print preview the document shows correctly.

Thank you

Joerene