I'm somewhat suspicious of the 1765 birthyear, much more so the 1767 birthyear.  Even granting the 1765 birthyear, he would have been a bit young to have fought in the Revolutionary War, but more importantly, men rarely married women three or four years their senior.

— born in Adams Co., OH:
5.  John Newton ROUNSAVELL, b. 12 June 1801 {48, OH}
6.  James Harvey ROUNSAVELL, b. 14 Nov 1809; d. 23 Sep 1871, IL; m. 1833, IN, Ann THOMPSON
7.  Lamina ROUNSAVELL, b. ca. 1800s/1810s; m. 25 July 1833, Tippecanoe Co., IN, Thomas CLARK
8.  George Whitfield ROUNSAVELL, b. 14 June 1812 {38, OH}; d. 1857, Iroquois Co., IL; m. 1833, Montgomery Co., IN; Mary Jackson FRAME

1.  Anon.  1966.  Marriage Index:  Ohio, 1789-1850.  Liahona Research, Orem, UT (Broderbund CD-400):

Rounsavell, Nathan	Curtis, Sarah	17 Oct 1815	Adams Co.
Rounsaville, Priscilla	Montgomery, Nathaniel	24 Apr 1821	Adams Co.

2.  Census Index:  Colonial America, 1607-1789 (Broderbund CD-310):

1741	Rouncevelt, Richard	NJ	Hunterdon Co.	Reading Twp.	p. 55
1741	Rouncevelt, Benjamin	NJ	Hunterdon Co.	Hopewell Twp.	p. 52
1782	Rounsivell, Benjamin	VA	Hampshire Co.		p. 25	06-00

There was also a Benjamin, Josiah, and David ROUNSEVAL in Rowan Co., NC, ca. 1755-1768.  These are all the ROUNSAVELLs (or variations) on the CD.  My guess is that ROUNCEVELT is probably closer to the original surname, which may be related to the Dutch surname ROOSEVELT.

3.  Census Index:  U.S. Selected Counties, 1790 (Broderbund CD-311):  the 1790 VA Census was destroyed, so we do not find our subject.  There are 16 ROUNSAVELLs (or variations) on the CD, found in NJ, NC, and MA.

4.  Census Index:  U.S. Selected Counties, 1800 (Broderbund CD-312):  the 1800 KY Census was destroyed; tax lists are substituted on the CD.

1807 Tax List	Rounsaville, Richard	OH	Adams Co.	p. 28
1809 Tax List	Rounsaville, Richard	OH	Adams Co.	p. 29

Other ROUNSAVELLs (or variations) on the CD were:  Isaac in Warren Co., KY; Josiah in Livingston Co., KY; Quick in Muskingum Co., OH; Job in Cumberland Co., ME; William in Plymouth Co., MA; Abner, Gabriel, Levi, Phillip, Thomas, and William in Bristol Co., MA; and David in Rowan Co., NC.

.  Census Index:  U.S. Selected Counties, 1850 (Broderbund CD-317):

1850	Rounseville, George W.	IL	Iroquois Co.	21st District	p. 180
1850	Rounsaville, John N.	MO	Scotland Co.	Mount Pleasant Twp.	p. 154

.  Emails from Joleen Axtell (Oct 2001).  In addition to most of the above information:

There is a migration from WV to Adams Co Ohio ca 1800 of the Richard Rounsavell's as one of their children is born there in 1801. Richard purchases 50 acres for $100 on Sept 22, 1802 from George & Susannah Rogers on the Ohio River in Manchester Twp Adams Co Ohio.(have deed)...