Printing page on envelope C5

Dear friends,

can you please help with this:

I have pdf form size A4 pages. In the form I fill up differenet fields. Some of them go into address fields, which I have on a next page. I would like to print pages 1-10 on A4 letter /form itself/ plus I have envelope size C5 and I would like to print page 11 /address where the printef form will be send/ on envelope in correct suze. Is there any script which I could trigger by button, which would tell the printer to print 10 pages on A4 size, double pages and then page 11 with address on envelope size C5, which I would be ready in printer in Envelope source? Or Is there at least any way of having Button in the form which would print only page 11 on envelope C5 /envelope is inserted in 90 degrees rotation/.

Thank you veeery much.